I haven't used an ad blocker so far, because I don't browse a lot of sites with ads, but have started seriously considering it when, last week, Youtube started to feed me with unskippable five minutes long ads. Five. Freaking. Unskippable. Minutes. Infuriating.
Fortunately(?), reloading the page made them skipped.
That sucks, and certainly would be frustrating. If something like that happens, sending feedback (right click and select “Trouble shoot playback issue”) can help (and no, those feedback reports aren’t just sent to /dev/null; they really are helpful!). Additionally, some employees have been known to lurk on r/youtube, but they might request the debug info for the playback (again, right click on the video; do this while the ad is playing and save it for later if you/someone needs it).
Disclaimer: I work at YouTube, but I’m just posting this in a personal capacity and don’t represent my employer in any way.
My favorite ad related story is I went to YouTube to see a movie trailer and got the very same movie trailer as the unskippable ad before the trailer :-D It's rare things get that good though..
Fortunately(?), reloading the page made them skipped.