Safari can't play youtube videos in Lion

[Steve-Jobs]

Hi,
I've just upgraded to Lion from SL, everything works fine but when I use Safari to watch youtube I get this error. Everything works fine with Firefox, but I get this error everytime I try to watch youtube. What could be the problem?

Thanks

 

[iforbes]

I would start by uninstalling the Perian plugin...seems like that is causing your problem, not Safari.