Netflix has some 4k content if you're on a streaming plan that says you're capable of using 4k, as do Youtube and Vimeo (if you pay for Vimeo). There's also a very small number of 2160p movie titles floating around pirate sites, though I don't know where those originate. Most humorously to me, there are a handful of porn sites that are probably the largest source of 4k content on the internet at the moment. Because the perfect test for your 70" screen isn't somebody's 2 hour HDR timelapse of Yosemite but instead a 20 minutes of some teenager getting double-teamed in resolutions high enough to diagnose melanoma.
