I read the description, and I understand that it's not the plugin's fault, but it really does suck how Firefox decided to complicate things like this. Now you can only play/pause, no next/previous track! 5 stars and a donation if this gets fixed. So sick of going back to the music tab.

Installed. Restarted Firefox. It just works. 5/5!

Installed this so I can use the play and pause feature on my Bluetooth headphones works like a charm. Previous / Next doesn't work with YouTube playlists from my experience but I can't imagine that being too far away.

Doesn't work with firefox

Doesn't work on my mac (at least for Google Play Music)

I was so enthusiastic when I pressed play/pause immediately after installing this extension. But so disappointed when I pressed previous/next to see that it doesn't work. Other media keys act as if you had pressed play/pause. Too bad, could you please do something to fix this ? Please don't force me to install Evil-Google-Chrome ;) (in Chrome it works out of the box :/ )
Windows 10, Firefox v66 (quantum), standard good old (more old actually) Logitech keyboard.

The addon works fine.... except that every media key is getting redirected to MediaPause when playing on YouTube. Would have given it a 5 star if it was able to properly skip a track instead of pausing it, if prompted.

Works as advertised for Spotify free. If only the bug preventing skipping was patched...