Testing out YouTube's 3D player with some old 3D test I made...(it's not supposed to be a perfect example)

Select the 3D view method from the drop down menu under the video. Try crossed eyed method if you don't have glasses.

Cross Eyed viewing tips:
http://www.starosta.com/3dshowcase/ihelp.html

To view in HD:
http://www.youtube.com/watch?v=89cGA4-yPRw&hd=1

More about enabling YT3D tags:
http://www.google.com/support/forum/p/youtube/thread?tid=56b6f6f15dabf994&hl=en

Watch it in Google Chrome 3D browser?
http://www.google.com/intl/en/landing/chrome/cadie/