A friend just asked for some help to download a video from facebook. I patched up a lil bookmarklet that does the download.
Get Facebook Video
Drag the Get Facebook Video button to your bookmarks toolbar in your browser.
Am sure there must be other bookmarklets that already that; guess I just wanted to do something else than my usual work. Anyway, usual caveats apply about usage of the bookmarklet - Use at your own discretion.
I didn't test it on anything other than Firefox 3.5. Must work other browsers as well, I guess.
I check if the current browser location is http://www.facebook.com/video/video.php. If not, this bookmarklet wont do anything. So, make sure u r in the video's homepage when u use it :)