http://applian.com/freecorder3/download.php

My son who is taking guitar lessons was wanting songs off of YouTube specifically
this one: http://www.youtube.com/watch?v=QjA5faZF1A8

This tool installs as a toolbar on the browser and you start it just before you click the video to start and start right after it finishes. It saves as an mp3 and you can configure it to prompt for a name right after the stop occurs

 I've used this company for something else called Replay Radio which is like Tivo for Talk Radio for over 5 years. Great product