An easy way to copy audio from YouTube

Yesterday I needed mp3 files of music from different instruments. I couldn't find very many mp3s to download, but there were TONS of different and wonderful examples of the music I needed on YouTube.

So how to get the sound from a video into a file I could burn to a CD?

I took a male-male audio connector and plugged one end into my audio out and one end into my microphone. Turned the volume down low and fired up my audio recording program, Audacity. Hit record. Switched to the YouTube and hit play. When it was done, switched to Audacity and hit stop. Trimmed the song to be just the part I needed, and exported to MP3. Burned. Done!