This might be known already but Ultraflix should be available in Yahoo store for Vizio TVs and perhaps other brands. ??
I helped a neighbor pick out a 75" Ultra HD and Vizio customer service informed me that the app can be downloaded to the TV.
I'm going to check it out this weekend and hopefully view and experience 4k streaming on what is a typical 4K TV sold in the market.
Maybe I can "sell" my neighbor on some paid content as well.