I didn’t noticed any flashes until yesterday, when I was watching a new movie. All other movies played fine (in this respect).
I think it may depend on the media type?
But for me the worst problem is that the refresh rate is not automatically change to 24hz.
I've read in the comments of that video that he is using a recorder that may be the cause of those problems, and connecting the box directly to a TV doesn't show the problem.
He also talks about replacing an HDMI cable that might have problems..
About the lack of 24Hz it would be a nice to be corrected in next OTA update..