The latest version of this extension 1.2.1009 doesn't work with the new version of Firefox 51.0.1 but I have used this for a long time and it has worked almost perfectly. I'm only writing this review to let you know about this incompatibility. When this is fixed, I will surely update to 5 stars if I can. Thank you!

Edit: It seems to be fixed on the current version 1.2.1010 so I updated the review to 5 stars. Keep up the good work!
Edit2: By the way, would it be possible for you to implement BTTV emojis too? Like :gun: :muscle: and :ok_hand: are all I need TBH
FeelsAmazingMan :gun: