How to download You Tube Videos

VideoDownloadHelper in Firefox
Realplayer SP.
use Orbit for this purpose.
http://www.onlinevideoconverter.com/

It’s Simple ,
1.go to www.keepvid.com
2.Copy & paste the youtube video url inside the box ,
3.Download the format you want ,(3gpp,mp4 (low/medium/high,FLV etc )

Another cool way to download the youtube videos..

Just replace the 'y' with '3' in the youtube URL. For example, if you are watching
http://www.youtube.com/watch?v=3Uz3wQRFbvg

Change the URL as:
http://www.3outube.com/watch?v=3Uz3wQRFbvg