We're seeing other weird reports about this too. We're going to add some logging tomorrow and push a build up for you guys to get on, so that when it happens again, we can hopefully have a better trail of activity that led up to the stopping, and what caused it.
Right now, all the logs show that it's stopping normally, not from any video playback issues. As if someone is sitting on the remote.
If anyone can provide more precise details on the behavior, it would be helpful.
Some people have mentioned that they get taken back to their Home Screen. If so, does the app start from scratch? IE, did the app crash, or did it just exit to the Home Screen and go into the background. Those are very distinct things.