The highest video resolution supported by the Nikon D810 is 1920 x 1080 pixels. That's over six times the video resolution of the most common video resolutions of 640 x 480 pixels (which is also supported by this camera). In addition, this Nikon camera supports a video resolutions of 1280 x 720 pixels. A video resolution of 1920 x 1080 pixels is equivalent to Full HD video. You will require a Full HD TV or better to appreciate this level of detail.
This camera's video resolution (1920 x 1080 pixels) is actually the best supported video resolution amongst all digital cameras of this age and spec.
The worst supported video resolution amongst similar types of camera is 320 x 240 pixels.