Getting sound off youtube?

I'm doing a radio assignment and I need to get sound off a clip on youtube. Does anyone know how to turn the sound into a file, that i can then use? I would seriously love you, if you did!

http://vixy.net

You can get the video or only the sound.

thanks soooo much! you saved my life!

No problem!

you can give me a good-rep if you want :devil: :p