There are a lot of checks and balances internally re: who's allowed access to user data, even in cases where it seems logical & obvious. Regardless how it appears externally, Google does take data privacy & security very seriously (to the point where sometimes it's painful trying to get things done).

For talking heads speaking clearly in English, YouTube speech recognition is improving noticably.

I recently started paying someone on fiverr to caption all of the videos I make. Costs practically nothing ($5 for five minutes plus tip), and is so much better than the YouTube auto-captions that it's not even comparable.