Thanks for the feedback. All BetterTTV emotes do work in the Firefox version too. You may want to make sure you've enabled both the BetterTTV Emotes and BetterTTV GIF Emotes settings in the BetterTTV settings.

Thanks for the feedback. After installing the extension you actually need to configure it in order to use the majority of its benefits/features. You can access the settings from within the chat settings of Twitch chat or the user dropdown in the upper right of the Twitch website.