Kiss YouTube!

Kiss YouTube offers an innovative approach for downloading video clips from YouTube. No browser bookmarklets, no software to install, just remember the KISS “Keep It Sweet & Simple” principle.
How does it work?
While you are watching a video clip on the youtube website, just add the word “kiss” to the front of the video URL in your browser address bar and hit enter. The video is ready to be saved on your computer in FLV format.
Example
youtube.com/watch?v=ls1954aa
becomes:
kissyoutube.com/watch?v=ls1954aa
Easy peasey! Give it a try!
(Source: Digital Inspiration)