Several choices.

First, and easiest is to use www.keepvid.com - enter the url of the youtube vid and click download and choose the MP4 option. In order to make it into an MP3 however you will need to use a file converter to convert it to MP3

Second choice is to download the latest build of (free) Real Player. After that if you hovver your mouse over a youtube vid you get a pop up to be able to save the clip to your computer (probably need to convert as per option 1)

Third is to use file2hd.com - enter the URL again, tick the box about reading the terms of service, and tick the box for MOVIES and hit enter. Save the MP4 and convert as option 1

Fourth is to download and install the FireFox web browser that has a plugin for saving youtube vids. Again, probably have to use a file converter to convert to MP3

And by far the simplest way is to PM me your email address as I already have it on my iPod and I'll send you it