Works well on a lot of sites, though it's not blocking everything related to Flash, as one can see here:
http://get.adobe.com/flashplayer/about/
Users complaining that it's not working at all should know that many videos don't use Flash anymore, but HTML5, and this addon is not designed to block HTML5 content.
https://www.w3schools.com/html/html5_video.asp

Could the icon placeholder be smaller? Currently it's too large.

But the icon is too large, smaller is better.