I would have posted this in the Beta Community, but I can't use the "New Topic" button there.
I just today (3/5/2020) used Testflight and downloaded the new beta of Channels. I returned to the top menu on Apple TV, then let it sit while doing something else. When I got back to it, and turned on the Apple TV by pressing the TV button (or whatever it's called - "Home Button?"), the beta version was selected and, above it, I saw the choices of what was playing now on my favorite channels. I picked a show and clicked on it.
Instead of going to the show, it went to the Playing Now screen. I picked the same show again. I got audio, but no video.
I tried going through the Guide. Still no video, audio only. And the audio continues while I have the guide or Playing Now screens up. I went to Recordings - well, the new layout is not my favorite, but since "Library" has what we used to have, I'm okay with that. So I went into the Library and picked a show and started playing it.
Again, sound, but no video. And even after I returned to the Library screen, the sound continued, only stopping when I exited out of the beta version of Channels.
The new menu, that comes up on the left side of the screen, instead of the top, is fine and easy to use. My big issue is the obvious: No video.
Now I'm off to see if I can figure out how to drop back to the previous version on Testflight.