HBO videos played ok, but after watching I was back to same window as before. No reward, just as if I had not watched it at all. Fortunately I haven't seen those anymore, because it was getting irritating playing the same video 5 times and always back to square one. Real Groundhog Day experiment.
Now I'm having problems with videos that claim that the reward is available in 3, 5 or whatever seconds. If I stop watching before the video has played to the end, I get nothing. So, I let it run to the end and then it gives me the reward.