People have found a comment exploit in youtube which hijacks the javascript.. I suggest stay awayfrom youtube or use Noscript while visiting youtube see example http://www.youtube.com/watch?v=ds9ddViCo2o which directs you to some bad site !
I think there are many hijackers that try to hack the site every day but sometime some of them succeed. but i think youtube is not a small thing. They have all the power and knowledge to fight back. No worries friends, happy watching.
It is very bad news. When I try to open the link "Youtube - worst.episode.ever" is displaying. I think youtube has fixed problem.
It might be possible but GIANTS like YouTube can recover in few minutes for sure. I just checked and everything seems normal already...