Display Oddity While Watching Video

[jbjtkbw007]

I noticed something.....off....about my phone while watching videos the other day. First off, I'm on the latest beta as of Monday/Tuesday. I was re-watching Black Mirror (episode was Black Museum in case anyone is wondering) and as I watched, I noticed my screen would occasionally dim, then go back to full brightness. It was like there was some interference, but more likely, it was like wanting to go to time out the screen, realize it was playing a video that was being watched, then go back to full brightness. It was the weirdest thing I've ever seen.

Has anyone else had this experience on their 9 Pro XL or any other Pixel? Never happened on my P8P.