I recently found a great software called
Vixy that allows you to convert YouTube files to many different formats. For example, you can use it to download a YouTube video and convert it to .MP4 format and add it to your iPod or another Video player. This program converts files to .AVI, .MOV, .3GP,.MP4, and .MP3. It can be downloaded for free at
vixy.net : Online FLV Converter : Download online videos direct to PC / iPod / PSP. It's free!.