How does vimeo pay for it's self if it doesn't have adds?
I've personally never used vimeo apart from the odd video. Don't even think I'm signed up to the site. I guess youtube is just where everyone else it, so that's where everyone goes. Ads don't bother me at all, and adds on my videos don't bother me, and I never associate an add with the persons video ever, I think everyone understands they're two separate things.
Youtube have recently made being able to monetize your videos much easier and available for almost anyone. So people are like oh my god I CAN MONETIZE MY VIDS NOW I'M GONNA BE RICH so you're going to see a lot more adds on a lot more videos.
I've never had any issues with loading videos, in fact my laptop can only just play 720, but can stream 1080 about 50% faster than real time.