Is that true that you tube ..

yea i think once when i downloaded a video from youtube and then switched it to flv when i was watching it my virus protection popped up. So yea i do think its possible. How they do it or put crap in the video i have no slight clue

No, even if someone where to manage to code malicios code into a mpeg, mp4, or avi file, when you upload to youtube they convert the file into FLV changing the coding of the file. therefore making it impossable.

I sure hope not.. I'm on there all the time! ;) but I don't think so.

It is possible for some code to be in a video file that your computer would then read and execute while watching a video. I cannot tell you whether this is truly happening as much on youtube as the rumors say.

There can be scripts typed ANYWHERE on the web that try install spyware, but YouTube doesn't process edit-able java or html on their vid pages, so I don't believe that's possible at all, unless you actually attempt to download [steal] the video & there's a virus written into the video's code.

Nah. When someone uploads a video to youtube it has to be converted into a different file format (flv..flash video). If there was any virus on a video I'm sure youtube would catch it.