I bet you’ve clicked on a YouTube video more than once and been disappointed when the No Longer Available message popped up.
To relieve your frustration just a little bit you can now find out why it is missing:
When YouTube videos are removed by the site’s administrators—in many cases the pulled videos allegedly violate copyright—they vanish without a trace. YouTube officials erase all data about such videos, including the title, author, and how many times the video had been viewed.
A new Web site by students at the Massachusetts Institute of Technology is preserving information about removed videos, and analyzing what kinds of clips are taken down.
YouTomb is currently monitoring 224618 videos, and has identified 4482 videos taken down for alleged copyright violation and 13783 videos taken down for other reasons.