So I've checked all the threads on the problems regarding viewing YouTube videos. For me, one videos work perfectly, the other one doesn't load from the beginning. It must be a Flash plugin problem as the same thing goes on in Chromium and Firefox at the same time. Switching YouTube to HTML5 won't fix the problem neither changing the Flash player's settings. I don't wanna nag about Adobe Flash and stuff, all I want is my YouTube back FGS! So is there anybody who has actually solved this problem?
I have same problem too. Tried every possible solution. Finally, installed tor browser bundle and now I can watch videos. I think it is not flash or other problem. May be restriction of your localation.