I don't know if anyone has mentioned it but the latest 9000 firmware (1191) not only adds MGO 4K (very limited selection) but also adds a Downloaded section to the 2nd UHD Drive. Not sure where we download them from but it looks like the drive will allow us to add content via download.
LG OLED 65C7P, Denon AVR-X7200WA, Apple TV, Oppo UDP-203, PS4, Xbox One
Nvidia Sheild Pro, HTPC, (2) Klipsch RF-82IIs, (4)RS-52IIs,, (1)RP-450CA,
(4) RP-140SA, SVS PB12-Plus, Emotiva XPA-100, XPA-200, Emotiva A-700
UN55KS9000, Denon x4200w, Apple TV, Panny BDT460, HTPC,
Nvidia Shield, Klipsch G-42,(2) R-3650-W-II,(4) RSL-C34E, SVS SB-1000, UPA-200