Here are some basic step by step guides that will show you how to download youtube videos to iPhone or iPod.
Best way to get FLV file from Youtube and convert for iPod or iPhone is via vixy.net. Works for Mac and Windows users.
Windows users can use AVS Video Converter that lets you convert FLV files to any file you can think of and it’s free too (see AVS4You)
Hope this short tutorial helps you get all the youtube videos you want on your iPhone or iPod Touch in our case.