Nikon Europe uploaded the official sample 4k UHD video from the Nikon D500 on YouTube:
The Nikon D500 can record 4K UHD (3840 × 2160)/30p/25p/24p as well as 1080/60p video for up to 29 min. 59 s¹, with simultaneous output via HDMI available. It is also possible to generate 4K UHD time-lapse movies within the camera. In Full HD or HD mode, the D500’s electronic Vibration Reduction function² reduces the effects of camera shake in the horizontal, vertical and rotational directions during hand-held movie recording, while Active D-Lighting preserves details in highlights and shadows to capture footage with natural brightness.
¹ Recorded in separate files.
² Image area will be slightly smaller in DX-based movie format.
The 4k sample video from the D5 was removed from YouTube for some reason.