what format do you mean? there's a google chrome add on, firefox, web page?i use www.youtube-mp3.org it's 'apparently' ok to use as the mp3's from it are sometimes poor quality
http://www.dvdvideosoft.com/products/dvd/Free-YouTube-to-MP3-Converter.htmThis for all your windows people. If you have a mac your gay Brilliant program.