Does what it sets out to do but the speed resets to 1x after holding the spacebar to go to 2x (should go twice the set speed in my opinion) and there's no link to any source code repository despite the plugin being licensed as MPL (which is why I rated it 1-star).

Extension is greyed out for me in the extensions menu and scrolling on the speedometer button in youtube does nothing; though clicking it does reset the speed to normal if I change the speed through the youtube menu like normal