What to use to extract audio from youtube videos

One addition to this below.

Bill in Co wrote:
I think my numbers were a little off here. As a more realistic guide,
I'd
say the following bitrates are roughly comparable from some of my limited
tests, in terms of artifacts, and using a DVD source file:

4000 kbps MPEG2 (like for a NTSC DVD at 720x480) (this, by the way, is
probably as low as you want to go without some appreciable artifacts)
1500 kbps Xvid or H263
1000 kbps H264 or WMV9

But take that with a grain of salt. :-) But I think it's in the
ballpark.

The addition being WMV9, which I found pretty comparable to H264.

But as I mentioned, I've switched over to MP4 (with H264), as it's more
universal and generally easier to deal with (for example, in demuxing and
remuxing out the audio and video streams, etc).