Apparently there are a lot of people having problems with youtube today.
I cannot view any video on youtube.com (only shows a black box) but strangely enough I am able to watch embedded videos.
I guess this is both a mac and a pc issue and is effecting firefox, IE and Safari (not sure about chrome)
Really i would give a shit less but today I am trying to build a video gallery for a website and it is making it a real pain in the junk.
Working fine for me.