After using AdBlock for a while with Firefox to block Youtube ads without any issues, I have started to have issues with Youtube since the past day or two.
What happens is that videos take long to load. I.e. I see a black screen and nothing happens, then after 30 seconds to one minute, the player client starts to try playing the video and eventually, the video starts to play. Here I assume that the point at which the player starts to try fetching the video clip from youtube servers is when the rotating circle of 8 round spots appears at the middle of the screen.
This happens with almost every video clip, also with clips that used to play fine without delay only as recently as a few days ago.
Here's what I think has happened; I think youtube has implemented some kind of a change to their system that punishes AdBlock users with this delay. Also, it is quite common that the play button and other buttons at the bottom of the player client disappears although they do work as intended when clicking on them, at least most of the time.