WikiHow has a detailed discussion on how to grab and place YouTube video on your iPod or other portable video player. Good news if you like 5 minute videos of kids skating with their hands.
Firefox (Windows only)
1. Add the Greasemonkey extension to your Firefox browser.
2. Go to www.userscripts.org and install the Download YouTube Video script.
3. The next time you watch YouTube, you’ll see a Download Video option beneath the screen. Click it to save the file to your desktop as QaQw9V4Upj4.flv or whatever.
4. Install and launch the free Super video converter (www.erightsoft.com). Download is located here.
5. Select Apple – iPod from the Output Container option, and then the output video codec H.264/AVC. Set size to 320 x 240. If you get an error message when converting, unclick the Use DirectShow button. Otherwise, drag the converted file into iTunes and it’s ready for viewing.
Safari (Mac only)
1. Go to a YouTube video page, wait for it to load, and open Safari’s Activity window.
2. Double-click the URL of the video file – it’s the largest one – to download it.
3. Rename the file something better than QaQw9V4Upj4 – say, Skateboarding Bulldog.
4. Drag and drop it into the free iSquint converter (www.isquint.org) and – presto! – an iPod-optimized video file for your iTunes library.
How to Watch YouTube on Your iPod [WikiHow]