How to download videos from all popular video sharing sites like YouTube, Blip.tv, Vimeo, MySpace and Metacafe?
Quick Answer: KeepVid.com
Drag the above button to your bookmarks toolbar. Next time you are in a video page, click it to get the download links.
In addition to the flv file, keepvid also gives you the link to the better quality mp4 file, if one is available.
KeepVid.com supports a large number of video sharing sites:
What other tools have you found useful? Please share in the comments.