Rated 5 out of 5 stars

Problem solved. See here: https://bugzilla.mozilla.org/show_bug.cgi?id=1144285. Installation of Visual C++ Redistributable Packages for Visual Studio 2013 removed the issue.

@Edouard Montas:
There is a forum for user support - http://forums.mozillazine.org/index.php.

And if you find bugs you should check https://bugzilla.mozilla.org/. If your specific issue is not reported yet, you can file a new bug.

This review is for a previous version of the add-on (3.3.3).  This user has other reviews of this add-on.