Works as intended but has an awful flaw described already in a 1 star review that I'm experiencing as well which states "Having this extension enabled makes Firefox randomly unresponsive and produces a massive increase in CPU and RAM, specifically the RAM increases until it fills the 16GB I have installed on my PC, then Firefox crashes. I checked in about:performance and verified that the cause was this extension, the resource consumption was very high.

When this extension is disabled, the phenomenon mentioned above does not occur."