I've never encountered that problem, maybe Google have fixed it by now, however, I've noticed another problem with a "world of tanks" ad. When it appears at the bottom of the video player screen when viewing a video, it shifts the whole video player screen to the right, so the buttons to change view size, and most importantly, to close the ad, are hidden and unusable. I'm not sure who's at fault here, but 2 different highly intrusive ads from the same company doesn't seem like coincidence, and I suggest Google stop showing "world of tanks" adverts for good