Edit: Something like this but for page not video: https://admanager.google.com/home/resources/feature-brief-dynamic-ad-insertion/. There is 1 i find called Kevel, has anybody here used and can give opinions? https://www.kevel.com/
Mind you, that isn't perfect and you can't really do that with third-party ads, but that is about what you can do.
The reason is pretty simple: my browser does what it is told from me. Normally that means render a site as seen, but it doesn't have to be and you can't instruct it otherwise.