Of course it’s easy as fuck. YouTube knows when it’s serving you an ad. They know the ad is x seconds long minimum. So if they really wanted to they could just stop giving you video data for that time and you have to sit there twiddling your thumbs.

A more elegant solution would be to block the video transmission until the browser returns a secret (which it only gets at the end of the ad break), no way to get around that.

If ads are not served every single time you could still get around it by opening up several connections so you can buffer around the ad breaks… but that’s a hassle and you can’t use this with an account (so no age restricted videos). And at some point YouTube might force you to make an account to watch.

If Google wanted to they could do it. Then in the absolute best case you’d have to sit there and watch a black screen for 5 seconds (you still load the ad, you just don’t display it).