It's a Nikon promotional video touting the (laudable!) low light performance of the new D750, which bests both the D600/D610 and the D810 and quite a beautiful video it is, although much of the credit goes to the soundtrack, which is even more evocative than the videography.
Unfortunately, after the D600 shutter-flinging-oil-on-the-sensor fiasco made purchasers of new Nikons wary about being first to buy, we now learn that people are having issues with file corruption in the brand new D750s, although from what we've seen, the problems seem to be limited to Sandisk memory cards. We hope that is the problem and not the camera.
Oh, look there's another low light test, taken with the D810, which didn't do as well in the dark, which isn't surprising given the unit's 36 million pixels, gross overkill for even 4k video (which the camera can't do).