Just found out how to download youtube videos without any plugin via keepvid .
AND I can download in HIGH QUALITY MP4 format now that youtube is putting videos in high quality format!
The video is H264 format and the audio is in stereo!

How to get it?
Well .. just add &fmt18 to the end of the youtube URL..bingo...just paste that into keepvid and we r in biznes!
example:
original URL :
http://www.youtube.com/watch?v=TwcXBT-N3Tw

high quality URL :
http://www.youtube.com/watch?v=TwcXBT-N3Tw&fmt=18
COOL!!!




If you are lazy, install this add-on to your firefox