I think one of the main reasons why people get more annoyed by ads when watching videos online than when watching broadcast/cable television (and certainly my reason) is because the former has no real filter against repeating the same ad too close together.
Watching just one episode on Crunchyroll, I just saw the same ad seven times; three times in one break; and yes, literally twice in a row. Which is worse than usual but not unprecedented.
Except this time the ad being repeated so many times was the worst kind of ad; a political ad funded by a superPAC.
(I started to dissect the horrible content of the ad itself, but it’s not worth the amount of time it would take to finish. It was simply a particularly extreme example of how ads for horrible candidates are often full of euphemisms and dysphemisms so inaccurate that they should be considered false advertising and slander respectively. And it told me exactly what I need to know to vote against the jackass it was for.)