Just found this great free program to convert .flv files to 3gp / aac etc.

In plain english, enables you to watch youtube clips on your mobile phone... If it supports video streaming of course...

< here >

Another good program for this is Clonedvdmobile - I use it for converting them into avi's for the Archos personal dvd but it will also convert to Ipod, mobiles etc

if you wanna download easily without plugins for this and that - just go to www.youtubex.com