Very nice. Rated 5 out of 5 stars

Nice Addon, working fine thus far.
It makes Flash Bug # 3223393 a little less pestering.

I have a suggestion, though. I'd like to be able to configure a default setting for flash to be deactivated on startup. So maybe you could implement an opt-in to "Deactivate flash on close" or something?

Edit: Good job! And fast. :-)

This review is for a previous version of the add-on (0.8.5.1-signed). 

Thank you for your suggestion. This sounds like a good idea to me and I will try to implement it in the next version.
Edit: Feature implemented!