Sometimes when you watch Youtube videos, you experience buffering. You can wait for a stream to be buffered completely by hitting the Pause button, and then use a sound recorder. The disadvantages of this approach is that you lose quality when recording, plus you can record in real time only.

If you download YouTube streams with software like Replay Media Catcher, you can do it much faster than in real time. Plus MP3 extraction allows to avoid lossy conversion, RMC 4 extract MP3 or AAC tracks from youtube videos losslessly. So the latter method is fast and lossless.

There are many other ways of downloading Youtube videos. For example, you can use Fast Video Download, free Firefox extension. After downloading drop your FLV or MP4 file onto freeware FLV Extract and it will extract audio tracks from your files losslessly.