I use Firefox and DownloadHelper to grab the video (saving it as an .mp4.) Then I use ffmpeg, with the lame encoder, to extract the audio track to .mp3.
ffmpeg -i "source.format" -vn -ac 2 -ar 44100 -ab 320k "output.mp3"
where -vn is no video, -ac is the number of audio channels, -ar is the audio rate and -ab is the bit rate. I use the settings in the original file to set these. Just to ffmpeg -i "inputfile.format"and look for the Audio stream section in the info dump.
Edit: I know the original is 127k but I used 320k as an example.
ffmpeg -i "source.format" -vn -ac 2 -ar 44100 -ab 320k "output.mp3"
where -vn is no video, -ac is the number of audio channels, -ar is the audio rate and -ab is the bit rate. I use the settings in the original file to set these. Just to ffmpeg -i "inputfile.format"and look for the Audio stream section in the info dump.
Edit: I know the original is 127k but I used 320k as an example.