I am Russian but am also fluent in English so I watch videos in both these languages. This automatic translation doesn't happen that often with my usage of YouTube, but when it does, it frustrates the crap out of me. So yes, I did look for a setting to turn it off, but didn't find any.

Relatedly, Google and Microsoft insist on showing machine-translated developer docs by default. A translate button is fine, but doing it by default?! I struggle to understand who thought that this could possibly ever be a good idea.