I've tried half a dozen volume boost extensions to make quiet youtube videos louder, and this is the only one that worked immediately on installation. (firefox 60.9.0esr on linux)

Test

I've not used it that much (just 2 times), but it does what is supposed to. I can increase the max volume so it is now a pleasure to listen youtube when songs are silent even at max volume!

The only problem is this extension "forgets" the sound setting. when you open a youtube video in a new tab, the settings are gone. you have to stop the video, click on the icon, then max the sound setting again. Great extension, annoying problem.

It's a very nice and clean tool. It will be even better if it can persist the settings trough page refreshes.

Nice little tool that dose exactly what it says it dose with no fluff.

Just a manual gain slider. No limiting or auto gain control.

id give ya a million bucks if I could ty

Very useful when it's needed

Awesome extension that fixes the poor sound volume of my 2011 MacBook Pro. I would give it 5 stars, if it were to permit speed controls. Currently, it always resorts back to 1x speed for videos when changing the gain.