Nice ! I was looking for a way to play/pause youtube videos via my bluetooth headset and this does the job perfectly.
Infortunately I'm not able to use the next/previous track inputs.

Works perfectly on MacOS, just make sure you set up the shortcuts.

Play/Pause only

Thanks for the update! Is there a chance to include the mixcloud handler?

Does not work, when firefox is not on top (so what sense are the media keys for then? i want to control the music, when it's in the background!)
Does nothing else than pause/play.
I could also use the space instead ...

ps: problems are well known since v56 and we are on v74 already without fix ...

Same problem as another user, this only allows me to pause or unpause.

No skip or last track functionality.

Corsair K70
-Google Play Music
-Youtube

not working, it only pause or mute sounds...

Не работают медиа клавиши в Яндекс Музыки.
Если настройки не делать, то любая медиа клавиша на клавиатуре кроме паузы/воспроизведения ничего не может сделать.
Если сделать настройки и сохранить, то клавиши не работают.

Works fine, but the browser window still needs to be selected for it to work.

Great extension.
- minor con: prev./next key == play/pause.
- major pro: works with external devices (e.g. wireless headphones).

Thank you so much for making this. This addon even works from a different window

oh, that's so sad that firefox developers ruin everything. Media keys doesn't work in the background. Perfect Firefox.
Absolutely useless Quantum