Edit:This may have just been a one time thing, because it stopped doing this

I'm guessing that youtube had and update, but when I have Ghostery activated none of the videos play. Hopefully this gets fixed in your next update, because this is a really good extension. The best way I can describe what happens is that the video tries to play, then the ad tries to force itself to play, then just as it starts, this extension gets rid of it, all of this happens on repeat within half a second and it just goes on forever.