Rated 1 out of 5 stars

It does not work. When I click it, I only get a small box. I am using the latest version of firefox, it worked before the update.

This review is for a previous version of the add-on (1.7.1-signed). 

Latest version works with Firefox 22 and later (as you may see in version information).
If that's not the problem then it may be a conflict with some other add-on.
I use it - as also other users - without problem.