Yep. Watched the third Hobbit movie that way (because, after the first two, I was only watching it to satisfy morbid curiosity)

I think youtube-dl even supports some of them, which would avoid the malware issue. Mining its supported sites list might be fruitful.

Yes, and they don't install malware. (At least, they've never infected me. But it's not like the media center PC is an unpatched Windows using IE and no adblocker. That'd be the honeypot (if I had one).)

Now I think about it, I haven't looked at them since Flash was a thing. Maybe they've improved in the interim.