I've been having some really strange issues with Youtube lately as well. Slow load times, 720p or higher take more time to load and while playing the video, it looses quality from time to time. Like it drops from 720p to 240p...
I'm not sure what your problem could be, but are you experiencing any issues with other websites? I'm not sure if this will help, but try changing a browser and see if there is any difference.
Tell me if there was any changes and if it didn't help, I will see if I can help you some other way.
Yeah I'm also thinking so about YouTube lately,YouTube has been very buggy for the last few weeks, my total view count has been all over the place.
Give it a few days, I'm sure they'll sort themselves out, I'm sure it's just the YT staff still laughing about how brilliant YT comedy week was...