I have a similar setup using Openelec Gotham on a NUC with Mythtv backend using hdhomerun prime on verizon fios. I'm trying to track down an issue and was wondering if you've experienced the same thing. It happens mostly when we are watching live TV on channel TLC. At what seems like random times the video freezes, audio continues for a few seconds, and then also stops. I have to kill the xbmc process, or reboot the box, to get it going. It's also done this when connecting from xbmc directly to hdhr prime via upnp. I've posed on the forums, but no joy yet. Thanks.