If you want to download music from youtube, and you're running Linux, I highly suggest trying the 'youtube-dl' python script from Ricardo Garcia
. There are quite a few flags supported for custom file conversions, including video conversion, but I'm mostly using this to download albums and songs.
yum install youtube-dl
youtube-dl -x --audio-format=mp3 --verbose https://www.youtube.com/watch?v=hbtQX8ZDyN4