Yeah, I'd like to know the same, as D800/D800E has a small crop, according to Nikon's site: "Also, in the FX-based movie format, the width of the image area is approx. 91% of that in the still image FX format."
I just hope we don't have this crop with the D810/D750, I haven't found a word about this yet.
The dpreview spec list shows these resolutions for video: 3840 x 2160 (30p), 4096 x 2160 (24p), 1920 x 1080 (60p, 50p, 30p, 25p, 24p), 1280 x 720, 640 x 480.
Edit: yeah, UHD 25p is missing.
It would be fine for me too, but I wonder how well the existing NX lenses perform on this body. We'll have to wait and see, as we don't have too many options here.
This is from the Metabones FAQ:
"Will Samsung NX cameras be supported?
No. Unfortunately, it is not possible to fit the optics inside the Samsung NX mount owing to flange distance and physical interference issues."