The kicker there is ... Nobody I know is going to think "wow, playback on this video sucks, I should disable my ad blocker".
Like, it wouldn't occur to ANYONE I know that a piece of software we consider necessary could be the problem, ESPECIALLY if everything else is working fine.
That's not even number ten on the list of troubleshooting steps and most people don't make it past one or two before giving up.
WTF were they thinking?