I recently bought an Android TV (Sony W850C). I've been having this one annoying issue which I don't seem to find anyone else having from my searches online.
The TV works fine. The Android & App navigation works fine. But after a few days, the screen cuts to black when a video plays. Mind you, only the video. Audio works fine, and if I pause, I can still see the navigation controls.
This happens to app apps. (Hulu, Netflix, YouTube, etc). It's frustrating as I have to do a full reboot of the TV when this happens. I doubt it's a hardware issue as I'm able to play videos fine when I plug in my Chromecast.
Has anyone else had this issue?
I had this problem also, but figured out how to resolve it, just can't remember what I did exactly. I remember it being stuck on one of my inputs. When I'd leave one input (such as HDMI 1), then go to the home screen, you could still see the solid green background from the HDMI 1 input when the device was turned off behind all the tiles on the homescreen. When this occurred, all my video streams would do what yours is doing. However, playing local movie files played fine.
If I remember what it was I did, I'll let you know.
One suggestion I can give you though is to go to Settings -> Apps. Find the app called Sony Shelf or something like that. Force it off, turn off notifications. It gets rid of that stupid row they added that just shows featured apps that you have installed or don't have installed and don't work. It also removes the only way to launch the Sony Select app, so you might as well go back to Settings -> Apps and force that one closed and turn off it's notifications as well.
This basically makes the homescreen look like stock Android TV again by removing bloat.
Also, make sure your TV is updated all the way: http://esupport.sony.com/US/p/model-home.pl?mdl=XBR55X850C&LOC=3#/downloadTab
Come to think of it, my TV hasn't had your issue since the last update. Might be why I can't remember what I did to fix it.