While you are watching a video clip on the youtube website, just add the word "kiss" to the video URL in your browser address bar and hit enter. The video is ready to be saved on your computer in FLV format.
For instance, if the Youtube URI is something like youtube.com/watch?v=ls1954aa, you can download the clip by adding the word "kiss" in front of the youtube.com domain name. Hence the final address becomes kissyoutube.com/watch?v=ls1954aa which will have the link to save that clip.
KissYoutube.com [Thanks Gina Hughes]
Previously published Youtube Video hacks on DI:
Burn YouTube Videos to DVD
Seach & Download Youtube Clips with Miro (formerly Democracy Player)
Watch Youtube Videos on iTunes or Quicktime