You might have noticed that even on Firefox (depending on your lists) YouTube may detect uBlock Origin on Firefox now
There's already a workaround (found, again, here), but I figured I would use this opportunity to tell people that projects like Piped and Invidious exist, which both allow you to watch YouTube without loading their ads, with improved Privacy and (in the case of Piped) even Geoblocking-Circumvention and SponsorBlock out of the box.
They're both great tools, and using something like LibRedirect you can even automatically go to Piped or Invidious when clicking/opening a YouTube link (and more).
Both don't load ads, but unless changed in the settings Individous may still make connections to Google/YouTube to load the video(s) themselves.
Bit of a shameless plug for these projects, but I figured this is a really good time to show these projects as I often see people asking what they are in threads on here
I don't think they can really. I don't work in that stuff, but skipping isn't included in YT analytics from what I've read. I would bet they rely on something like average view percentage to just make assumptions. For example, if a content creator places the sponsor bit in the first 10% of the video, and average view percentage for that video is 80%, then it is assumed the sponsor bit was watched. I wouldn't be surprised if sponsors require some form of transparency in analytic reporting for content creators to get paid.
I also would figure that YouTube, as it has no bearing on their revenue, is probably not going to add in analytic features for Skip just for the sake of some third party.
Pretty sure you can see the parts people see more on average (otherwise I assume the viewer interest graph on the track bar wouldn't be a thing)