Question.
Wouldn't the catch-all solution for YT is to pair the AJAX calls for the video with a "view video key", and that key to be found out after running a deeply obviouscated javascript served with the html of the "view video" page?
They could even bundle some of the key-building-js with the ad being served.
At some point in order to "block the ad" , the ad blocker would have to run or analyze tons of JS code , making the ordeal to difficult to compute.
I think that is actually what they've already been doing for at least a decade?
Whenever you download a youtube video using something other than a js-enabled browser, then I think something like yt-dlp's jsinterp.py needs to evaluate some javascript to extract the key.