I really love this addon. If support Android Firefox browser，That will great!

It was greatly working on youtube and another regional portal i'm use to visit, but lately it stopped to work on both websites. It's a great tool, thank you developer!

I use the same extension in Chrome as well. It supports Youtube Videos.

For Spotify Web, you need to install this add-on as well: https://addons.mozilla.org/en-US/firefox/addon/spotify-csp-clear/ The developer is working on improving this GlobalSpeed plugin so that it won't need Spotify CSP Clear in the future.

I'm using this plugin to help practice the bass guitar during covid quarantine - slowing down the songs/videos to help me to learn the song.