Rated 4 out of 5 stars

CYS worked in the past fine for me, also now seems to do the job. So far so excellent!
However: now on a new system I find no longer an option to save my settings; the selection of formats I make gets ignored completely and the preferences window has only a "close" button, no "save" to be found. FFMPEG path is remembered and and also the columns. They do not fit into the detailed menu, though.
So at the moment the usability has (minor?) glitches, but the functionality seems to be complete.
Therefore only 4 stars for a 5 star addon.

System: FF 30.0 CYS 5.3.0 under SolydK, system up-to-date
(and yes, I restarted FF several times...)

This review is for a previous version of the add-on (5.3.0.1-signed). 

Thanks for your review. We've had no problem in CentOS. This sounds like it may be a possible corruption, please install CYS into a new, empty profile and let us know if it solves your problem (cytsaver@hotmail.com), thanks.