If there is an app for such for your TV on http://www.lg.com/uk/support/guides/tv/smart-tv/apps (this is the uk site, but your TV will use your local site): download, install and enjoy.
If there isn't such an app, you'll need additional hardware (for example a PC with a 4K player and videocard and a hdmi-cable), or a Bluray burner/reader.
Hi, I have managed to download films in 2160p 4K Ulta HD Bluray (265 HEVC 10bit) .mkv, size varies between 22Gb and 65Gb, How can I play these on my LG 43UH61 TV
Many thanks for any help you can give. B.