Download YouTube videos right from the video’s landing page just by changing the URL. All you have to do is swap the “Y” in the URL with a “3” and you are taken to a download page for that video.
Example:
http://www.youtube.com/watch?v=QuPwwGEeSLo
changes to
http://www.3outube.com/watch?v=QuPwwGEeSLo
That’s all there is to it. Quick and simple.
UPDATE
It looks like YouTube has made it so this trick doesn’t work. However, you can get around this problem. Instead of just replacing the “Y” with a “3”, you can replace the entire word “youtube” with “voobys” and it will take you to a download page.