I’m using the latest update of Mac and hearthstone’s video goes out. I don’t see anything, just a black screen with sound. I have found a temporary fix but I do hope it remains temporary because in the long term it’s quite a nuisance.
For others out there who need a quick fix. Just edit the option file in application support folder. You can access this from the library. Add the line “fullscreen=False” if it doesn’t already exist and then you can go back into fullscreen after.