я никогда не видел, чтобы

I've never seen …

→ я
phrase Uncommon #19,738
I've never seen … Introduces an action someone has never been seen doing. «Видел» is used by a male speaker; a female speaker says «видела».
RU: Я никогда не видел, чтобы он танцевал.
EN: I've never seen him dance.