full-on facebook comments, full-off youtube comments
When I decide something is a good idea, I commit to it gangbusters style. Being that I've had such a good experience with my Facebook fan page so far (which has 30+ fans now), and that the comments/discussion there is actually good, I changed all my YouTube videos to accept no comments, no ratings and have descriptions all point to the fan page. I edited all 150+ of my videos to reflect this and yes, it was a huge pain in the ass to get done but I felt it was the proper thing to do.
Why proper? Because YouTubers don't care if they lose their accounts or not while Facebookers do.
Anyone who uses Facebook regularly puts a good deal of effort into it over time. Contact/Friend lists are built, networks are joined, apps/games are set up and so on. In other words, people genuinely care about their Facebook accounts. There are many Facebookers who would readily say "My life is in there!" and mean it. This means they're protective of their Facebook identities and really, really don't want to lose them.
With YouTube there are two types of users, content creators and commenters. Content creators are the ones that make videos and care about their accounts while commenters don't make videos and couldn't care less. The bulk of the YouTube audience is commenters. If one of those types get kicked off the system, it's no big whoop because few truly use the Friends feature and accounts can be created in less than 45 seconds.
When you whittle it all down, YouTube is great for video content but nothing else. If YouTube disappeared tomorrow, nobody would truly care. If Facebook disappeared however, everybody would care because it's just that much more important in the internet social way of things.