I have the AppleTV HD (4th Gen) with the latest version of the AppleTV Beta installed and I’m having a weird issue where the video is stuttering, but the audio plays fine.
Here are the scenarios that I’ve tested
Experimental Player enabled and subtitles disabled - stutters
Experimental Player enabled and subtitles enabled - stutters
Experimental Player disabled and subtitles disabled - stutters
Experimental Player disabled and subtitles enabled - plays fine
By going by the list above, the only way that the video will play fine is if I disable the Experimental Player and enable subtitles and any other combination will result is stuttering video right from the beginning. Oddly enough this issue is only happening with a specific TV series. Anything else (TV or movies) have always and continue to play just fine in all 4 scenarios.
I should also mention that everything plays fine on my Mac (public release) and my iPad Pro running the beta.