Well, this is a tough one. You've got two steps: get the video from YouTube. Then get the audio from the video. I deal with the second in episode 139. http://macmost.com/converting-video-to-mp3-audio.html
The first is a tricky subject. The creator of the video may not want you to be able to rip their video from YouTube. Some, like me, make the video available (a podcast in my case), but others are more protective. You may want to check with the creator of the video first.
There are programs and techniques that you can use to get the video from YouTube to your Mac, but I've never tried them for the above reasons.
Well, this is a tough one. You've got two steps: get the video from YouTube. Then get the audio from the video. I deal with the second in episode 139. http://macmost.com/converting-video-to-mp3-audio.html
The first is a tricky subject. The creator of the video may not want you to be able to rip their video from YouTube. Some, like me, make the video available (a podcast in my case), but others are more protective. You may want to check with the creator of the video first.
There are programs and techniques that you can use to get the video from YouTube to your Mac, but I've never tried them for the above reasons.