Dirpy is a new (beta) site that allows users to upload YouTube videos and extract the audio. This is ideal when all you need is that hard to find song/blurb/quote that can only be found on YouTube. I'm not sure what kind of permission rights come into play, but anything "common craft" should be just fine.
What makes Dirpy so good is how easy it is to use. Just upload a YouTube video (via a URL), adjust your settings and file size, and click download to Mp3.
Give Dirpy a try by clicking here.