Your current choices are Netflix and Blockbuster streaming services, with perhaps more to come in the future. If you have video saved on your computer as media files, you can serve them yourself with DLNA.
I'm running the FL/FR outs into the analog inputs of an older Yamaha receiver and did not use the down-mix setting but left it at the default setting. I'm not noticing any loss of information and the music quality sounds good to me. You might give that a try and see what you think. YMMV.