really a must-have addon if you don't want your retinas to be burnt to a crisp on a daily basis. i'm rating it 4/5 because it has helped me for so long, but sadly the past days its been having issues with youtube to the point where i can't have it activated at all for it.
every time i try and activate it and refresh youtube homepage, the browser is about to crash and it asks me to stop this addon specifically. when i pause the addon, it works fine and i can refresh youtube without the browser almost collapsing.
were this to be fixed, then its an easy 5/5 for me.