Fireflybob
Copy the url into:
http://www.ripzor.com/youtuberipper.html
you will then have the video downloaded onto your hard drive.
Save the file as: e.g: "FILENAME.MPEG" or "FILENAME.AVI"
then search for a programme called "videozilla", this will strip the audio from the file into mp3 format.
Happy surfing
Any probs, pm me