Would you pay to watch if I record my interview coding challenges live?

No. But if I get to read the challenge first, you might pique my interest if I cannot solve it myself. Ultimately I still wouldn't pay for the answer, but I would be more interested in it.

Interview Cake makes 7 figures per year in revenue, I've heard.

For just videos — nope (ton of them on YouTube).

For a course, that makes me ready to tackle interviews in top companies without fear — YES PLEASE take my money right now!
But that's:
- videos
- practice challenges (ideally — with feedback AND timing)