I've seen playback pause twice this morning while watching NFL Network on the latest tvOS beta. Submitted diagnostics both times. Playback completely stops and the scrubber returns to the beginning of the buffer.
The first time it happened, when I exited to the guide afterwards the guide info for only NFL Network (6192) was completely gone until 7pm, even though the guide info was fully populated in the web interface and came back immediately when I force quit the app and relaunched. I did not notice this the second time, although I exited to "On Now" so it may not have been visible.