Work very well. Tnx!!

Dose not work.
Each slider can move but sound is not changing at all.
Other Equalizing addons for Firefox dose also not work.
But same addons can work in chrome.

1 of the Top 5 Browser Extensions of all-time...

I use this extension because at times I bumped in a video with only mono sound. It's annoying. With this extension I can click the Mono flag and the audio will play on both sides. You can also change the actual equalizer which can also be cool. :-)

удобное спасибо

Works well. I needed to refresh the tab YouTube was on after installing, but no big deal. It really helps me correct a number of audio problems on videos such as too much/too little: bass; treble; mid range; quiet voice overs; background noise and such. Thank you! :-)

So far, so good!