You can use any video you find, assuming it's the right format.
For a quick, easy, and free YouTube downloader, use Vixy.net.
It converts and downloads the files in an iPod format, though it adds a few seconds of the Vixy logo to the end. Not a big deal.
I also use a program called VideoGet, but it's not free. It will download from many sites, and convert them to just about any format you want.
iPod 4G 20GB | iPod 5G 30GB | iPod nano 1G 1GB | iPod touch 16GB
"You roll on the floor drenched in smiles and smoke and you're laughing your head off at something misspoken."