Rated 4 out of 5 stars

It looks good but I prefer fullscreen mode. There is no customization except you can give the button where you like it (which is important for me).

This review is for a previous version of the add-on (1.0.1). 

customization -> That come sure!
My firefox addon will receive soon all the features like the Chrome extension:
https://chrome.google.com/webstore/detail/bfbmjmiodbnnpllbbbfblcplfjjepjdn

Take a look on Google Chrome.
Thanks for you feedback!