It's called 'Video Speed Controller'. I try to minimise addons but I couldn't get by without it. 'd' key speeds up by 0.25 and 's' slows down by 0.25. It works on videos on most sites, not just youtube. Also handy are Youtube default shortcuts: right arrow to skip 5 seconds forward and left arrow for back 5 seconds. Tap them a bunch of times to skip product placements or long intros. Just a warning when you use these a lot it will make regular TV unbearable (if it isn't already).
First time seeing this. Are the timestamps crowdsourced or AI generated? In your experience how accurate is it? I notice it's got <1000 reviews. I can see this really taking off in the next few years. Thanks a lot for the recommendation, I've installed it and look forward to seeing it in action.
Timestamps are crowdsourced, not AI generated (AFAIK). It is 100% accurate of most of the videos. Since it is crowdsourced, less famous videos or videos with less views won't be skipped during the sponsor content, but we can be a good citizen and add the timestamps ourselves to help others.