The French Professor Loophole

October 20, 2026

I'm working on a language learning app which has you practice understanding sentences. Some of the sentences come from movies, and so I wanted to be able to show the actual movie clip where that sentence was spoken. The first question: Is it even legal to use movie clips like this without permission of the rightsholders?

Using the clips

In my opinion, the answer is clearly "yes". The reason is that you don't need permission if your usage falls under fair use. There are four pillars to fair use. At the end of the day, it's a judgment call, but judges are likely to consider something fair use if it scores well against these factors:

Purpose and character of use: Is the usage noncommercial, educational, or transformative?
Nature of the copyrighted work:
1. Is the source work factual/informational (like a news broadcast or biography)?
2. Has the source work been published?
Amount and substantiality: Is it using only a small amount of the source work?
Effect on the market: Does it have little effect on the source work's market value?

Luckily for me, showing short movie clips in a noncommercial language learning app fully saturates factor 1. I'm also using a very small amount of each movie, and it should not have any negative effect on the market for the movies. I also win on 2(b) because the movies I use are already published (and in fact they tend to be pretty old).

The only factor I lose on is 2(a), because movies are necessarily creative, not factual/informational. But to be fair use, you don't have to satisfy every factor. Instead they're just the general guidelines. I would be worried about this, but luckily, Google already went to court about this so I don't have to. When Google Books was trying to digitally archive all books in existence, they were sued by the Authors Guild. But Google won, and the judge in the case mentioned that the second factor rarely plays a significant role in actually determining cases:

"The second factor has rarely played a significant role in the determination of a fair use dispute. ... If one (or all) of the plaintiff works were fiction, we do not think that would change in any way our appraisal."

There was another case that was even more similar to my situation. In 2003, the publisher Dorling Kindersley (DK) released Grateful Dead: The Illustrated Trip, a 480-page coffee-table book explaining the full story of the Grateful Dead. DK wanted to include 7 images of original concert posters and tickets from historic Grateful Dead shows, but the images were owned by Bill Graham Archives, who wanted to charge $2,500 per image to license them. DK basically said "nah" and just included them anyway without paying.

Of course, they got sued, and their situation may seem even more dire than mine. They were using the entire poster (factor 3), in a book they were selling for profit (factor 1). But despite that, the court held that it was fair use. For factor 3, the posters were shrunk down to fit in the book, rather than reproduced at their full size. For factor 1, even though they were selling the book for profit, they were still using the material for educational purposes. But just like me, the only one they clearly lose on is 2, because posters are creative works rather than factual. Despite that, the judge said:

"We agree with the district court that the creative nature of artistic images typically weighs in favor of the copyright holder. We recognize, however, that the second factor may be of limited usefulness where the creative work of art is being used for a transformative purpose."

So I'm just basically going to ignore the second factor and hope that it doesn't come back to bite me. Unfortunately, the second factor is the least of my worries. Because while I can freely use the movie clips, I still have to somehow acquire them first.

Acquiring the clips

This is where the law gets really strange. Basically, if you do things the easy way, you break the law and go straight to jail. But if you do everything in an extremely convoluted way that helps no one, you're totally fine.

As we all know, pirating movies is illegal. It's illegal even if you're going to use the pirated movie for a lawful purpose. Just downloading it at all is a problem.

Now I seem to be in a pickle. How can I get the movie clips if I can't illegally download the movies? Well, it's natural. I can just buy used copies of the movies on DVD, then rip them off the DVD onto my computer. But surprise! That still isn't legal. That's because DVD and Blu-ray movies have DRM, and circumventing DRM is illegal.

Well, mostly illegal. There is actually a privileged class of people who are allowed to circumvent Blu-ray DRM. This consists of an elite caste of librarians and educators, who are above the law and can rip clips from as many DVDs as they please for their classes. But even for these people there's an issue.

You see, when Congress created the DMCA, they banned two things:

"The Act of Circumvention": It is illegal to descramble a scrambled work or bypass a digital lock.
"Trafficking": It is illegal to manufacture, import, offer to the public, provide, or otherwise traffic in any technology, product, service, or software primarily designed to bypass a digital lock.

When Congress wrote the law in 1998, they added a safety valve allowing the Librarian of Congress to grant exemptions for educators and so on. But they explicitly wrote that those exemptions only apply to the ban of "the Act of Circumvention". So thanks to the exemption, a French professor at a university is 100% legally allowed to bypass the AACS encryption on a Blu-ray to grab clips for their class. But it's illegal for anyone else to give, sell, or host the software that the professor needs. Even the university's IT department isn't allowed to build a ripping tool and distribute it to the faculty.

Ok, let's put ourselves in the shoes of the French professor. You might have a computer with an optical drive. You put the Blu-ray in, and your computer can read the bits on the disc just fine, but because the movie is encrypted there's no way to play it. You'll need to buy a special program that has the decryption keys. But that program doesn't let you download the movie, it only lets you play it, and it uses the Protected Media Path, which means the movie is decoded in protected GPU memory and sent directly to the screen, without any normal software on your computer ever seeing it. That means there's no way to even use screen-recording tools to record it. But okay, your graphics card is plugged into an HDMI cable that's plugged into your monitor, so what if our French professor buys a device that plugs into HDMI the same way but records the input?

Well, they thought of that too. Once the video leaves the player and travels down the HDMI cable, a second layer of armor kicks in: "High-bandwidth Digital Content Protection", or HDCP. How this works is your monitor actually has encryption keys built into it, which your graphics card uses to encrypt the HDMI stream along the wire itself when the Protected Media Path is enabled. And they don't give those keys to just anyone; monitor companies have deals that give them access to these keys. To decrypt it, you need your TV's unique decryption key. That key lives in a dedicated hardware block inside your TV and never leaves. It can only be extracted by an extremely difficult process that involves dissolving the chips in acid and then analyzing them with an electron microscope.

Of course, perfectly securing these keys distributed across millions of TVs is difficult, and a few manufacturers got lazy and didn't store them properly. As soon as this was discovered by pirates, those keys were extracted and immediately were used to extract Blu-ray content. Hardware hackers would hunt down these TVs, extract the key, and then package it into a special cable that strips the encryption that they would sell for a few hundred bucks.

But Intel had another trick up their sleeve. Remember, every TV has its own key. So they created a list of keys given to these lazy manufacturers and programmed newer Blu-ray players to not work with those keys. This is called "revoking" the key. But for a player to stop accepting revoked keys, news of the revocation has to reach each player. Because Blu-ray players usually weren't connected to the internet, that's pretty tricky, but Intel had a wise idea. Every commercial Blu-ray disc includes a list of all revoked keys, and when you put the disc in your player, your player will copy the list from the disc to the player's internal memory. This means that as soon as you enter a new Blu-ray disc, your player will never accept one of those revoked keys again.

But the pirates' technology advanced. Legitimate companies were licensing keys from Intel and putting them into decryption chips to sell to TV manufacturers. But people in Shenzhen would set up shell companies and buy thousands of those chips, put them into HDMI cables that would decrypt the video stream for you, and then sell them for $15. Intel and Sony were running around trying to stop those sales and revoke any keys they could find, but it was a game of cat and mouse. It was a bitter fight on both sides. Until everything changed in 2010.

You see, Intel made one fatal error. The gold standard for this type of encryption is called "asymmetric encryption". But asymmetric encryption is computationally expensive, so Intel designed a method based on the much cheaper "symmetric encryption". They generated a single, master secret, a 40x40 matrix of numbers, which they used to generate every key they gave out to TV manufacturers. Because the Blu-ray player's keys and the TV's keys were both generated from this master matrix, the two devices could mathematically agree on a shared secret over the wire, but only Intel could create new keys, because only they had the master secret.

But in 2001, a Carnegie Mellon cryptography researcher discovered an error. If someone could get about 43 TV keys from different sources, it would be possible to reconstruct the original 40x40 master matrix that generated all the keys. It required some care to do it perfectly, but the basic algorithm is based on Gaussian Elimination, a way of solving a system of equations that many people learn in middle school. Once done, you'd have the master matrix that was used to generate every key. But still, to do it, you'd need about 43 keys, and those keys were locked up tight in these chips that were nearly unhackable (short of an acid attack).

No one knows exactly what happened next, but we can speculate. When a hardware company paid Intel their $15,000 annual license fee, Intel literally sent them a batch file containing a block of 10,000 unique keys to program onto their production line. Any insider who had access to that file could have discreetly copied 50 keys onto their personal computer and taken them home. We don't know if that's what happened, but what we do know is that 9 years later, the master key matrix was posted online by an anonymous Twitter account. And now that the master matrix is out, anyone can easily make a decryption key that will be trusted by every Blu-ray player. These keys are indistinguishable from the ones inside millions of everyday TVs, and so even though Intel could change the algorithm, they don't want to break all those old TVs.

Life goes on, and soon it was time to update the Blu-ray standard (and Blu-ray players) for 4K. All 4K TVs were new, so Intel had a chance to say "the pirates beat us last time, but if you want the 4K stream, you'll have to use our new encryption method". And they hoped to do a better job for the new method than they did for 1080p. Determined not to repeat their mistakes, they threw out the flawed symmetric encryption design and switched to standard (and unhackable) asymmetric encryption.

Standard 1080p Blu-rays still use the old, broken method so they don't brick older TVs, while 4K Blu-ray discs strictly require the new, unhackable one. But even that was only marginally helpful, because companies in Shenzhen have turned "start a shell company, buy new 4K decryption chips from legitimate suppliers, and put them into an HDMI splitter that strips the encryption for you" into a science. And the result is that such splitters are still easy and cheap to buy. However, these are inconvenient for pirates because they require you to just record the output of your Blu-ray player. Meaning, if you want to capture a 2-hour movie, you need to let your Blu-ray player play it for the full two hours, and use a "capture card" to record it, which forces it to be recompressed (losing some quality) among many other issues.

A legendary hacker by the name of mike_admin has developed better methods, but this one will work for our French teacher. It's illegal for most of us to circumvent DRM this way, but a French teacher can, and as long as they do it all themselves, no one will have broken the law.

Or, you could do it the easy way. You can put a camera in front of your TV, hit "record", and grab your clips that way. Light traveling through the air isn't encrypted, so you haven't bypassed any DRM, and somehow that's 100% legal for anyone to do.

For Yap, the exact details of my clip-sourcing pipeline are a closely guarded trade secret, at least until I hear back from my local community college about whether I've been accepted for an adjunct French professor position. What I can tell you is that hearing a sentence spoken in the wild by a real actor, with the emotion, pacing, and background noise of an actual movie, is basically exactly what you need for working on your language comprehension. If you want to see the end result of this absurd journey, you can check out Yap here.