DS Video is an app from Synology, I'm sure it's an easy port from the Android counterpart.
I also wish to connect a Sub Woofer to the system. The sound on the 79 inch is good enough for my home use, just lacks some base. If I could connect an external sub using the RCA cables it would make my uncluttered living room more appealing. But I have to choose either internal or external speakers currently, thats a bummer...