Listen to only the audio on YouTube without loading the video.
This userscript add a toggle to switch audio mode on Youtube.
I've found the original userscript on Github: https://github.com/teaqu/youtube-audio-mode but it's not working anymore so I've opened an issue. After a month without receiving a reply I've decided to update the script myself. The first thing I've noticed is that the issue I've opened was totally wrong.
v.0.2.8