Here’s an easier way to rip the audio track from a Youtube video:

1. Copy the link of the Youtube video. For example, I’ll take this one. Paste that link into the text box on this site.
2. Change the dropdown menu from ‘AVI for Windows (DivX + MP3)’ to ‘MP3 (audio only)’
3. Press Start. It should now say ‘Connecting to Server,’ then ‘Resolving Video URL’ and then proceed to convert. Get a coffee while it converts for about 40-45 secs. or more depending on the length of the clip. It should download to your desktop (or other selected folder) in .mp3 format
4. Go into whatever program you’re using to make the mashup, and drag the mp3 file in as you would any other track, or alternatively select it from the Media Browser.

If you want to download the video as well, I don’t recommend using that site. Go here to get something called Greasemonkey and then here and click the Install button (and then confirm) for something called YousableTube that will put a link to directly download the video right next to any video.