You can download video from YouTube, then open the video file in Audacity if you have ffmpeg installed in Audacity.
Doing that is quicker & more reliable way of getting a copy of the audio than recording the streaming YouTube.
Download the highest resolution version of the video you can find, as it will usually have the best quality audio.
Use RMS normalize plugin, set to the same value, on each individual track, for more consistent volume between tracks.