If I'm watching a movie I probably want to quality to remain reasonably high, if I'm watching a Youtube video of people talking or something where visuals don't really matter I'll take 480p over buffering.

Youtube is pretty decent for that, you can either let it figure out what format to use, or force the resolution. That's a good compromise IMO.

Video quality is more important for coding instruction than movies, imo. If you can't read the code or gets blurry, the feed becomes nearly worthless.

I agree that here auto-bandwidth adjustment is the wrong answer here and would not be appreciated by the author's paying customers.

I've pretty much switched over to youtube-dl for video viewing, as I find it to be superior to the web interface in most ways. I get the highest-quality file every time, instead of what their AI thinks I want. I can easily request audio-only or video-only. Download once, watch over and over without using more bandwidth each view. No suggested videos. No recommendations. No comments.

It can be. Especially users on mobile connections which can have quite low bandwidth caps.