Invisible Youtube loading bar for Firefox 5.0.1 (9/14, it fixed itself?)

 Spoiler

I can't replicate your problem, you might want to try reinstalling/updating Firefox? We're up to 5.0 now.

I actually have a problem exactly like this when I use FireFox ONLY when I change the size of everything for the browser. When I make it smaller to fully see my YouTube channel background I have this problem when I try to view all videos in 420p+ but if I go back down 1 size to what it was before everything was fine again.

Edit: After seeing this I went back and changed my size, tried out a few videos and it seems to be fixed..I just recently updated to 3.6.22 since I don't like the layouts and shi't in the new one. So kind of happy about that now, hope it stays fixed! xD