Youtube is probably varying the rate of ads displayed for each user based on some factors. I was watching an hour long interview and was shocked that I was served a 30 second ad every 3-4 minutes. I scanned the comments for outrage, but there were no negative comments. I think YT may have increased my ad rate because I was using a VPN.
I think they will use ads as a form of tax, to discourage certain behavior, and even certain content. I think I notice this more on libertarian leaning videos (although I definitely haven't done any rigorous analysis re that).
Can't wait for the day everything is decentraly hosted, and we access it through whatever portal we want.