Works good but not perfect. Rated 4 out of 5 stars

Works pretty good, but as someone else pointed, Firefox has to be in focus. It would be awesome if the hotkeys were global and could be used when outside Firefox.

Also, how about being able to customize the hotkeys or even apply them to the "Play", "Next", "Prev" media keys that come in some keyboards.

This review is for a previous version of the add-on (0.2.1-signed.1-signed). 

Thanks for the review. I'm glad you like the functionality. I am sorry to say that I do not have plans for adding any global key controls to this. I may in a future version add the ability to assign your own keys.