Youtube - Is anyone else battling to view videos?

Since I installed the new Firefox on my mac I have been unable to view a majority of videos on Youtube. The video section is blacked out with the text: "we're sorry this video is no longer available". I can't view videos in any of the browsers and have spoken to other mac users (I think it is a pc problem too though) and from my research on the net it is a fairly common issue right now, but I haven't been able to find any solutions.

Does anyone know what is causing it, and more importantly, how do I make it stop?!

Thanking you in advance
Youtube Withdrawal Sufferer