Hey Quark, there are all kinds of programs that will rip audio straight off your soundcard. I don't advocate stealing music from musicians though. If they wanted you to download it for free, they would enable that.

The bit rate of youtube videos tend to be quite low. I have a few videos from concerts and they aren't nearly as clear as my original copy. That's why you don't see as many artists removing the rips people put up there. The quality is so low that you can't really play the tracks you rip the audio from.