Cool stuff, but wish there was a disclaimer saying many of the things here are Chrome-only. The target audience for this might not consider browser compatibility from the get-go and have to re-think their UI later.
> the impact of sponsor sections can only be measured based on the total views of the video
I don't think that's true at all.
1. There are video analytics to measure what parts of the video were watched.
2. Even if you generally dislike ads, there is a chance that you will see an ad you are interested in that you will check out, which will contribute to the ad's effectiveness, and can be measured. If you automatically block ads, the effectiveness becomes 0 in all cases.
To be honest I love "mech keyboards" not really because of the mechanical keys, but because people make them in so many customized sizes and colors. But there's not really a good term for this as far as I'm aware.