Nikon have seriously pushed the video boundaries in DSLRs, I'd say that video is almost as important to photography to them. Try out the video capabilities and you'll be amazed.
I've shot a few hundred hours of video on my D800 and I am extremely pleased with the results. However, I'm not so certain Nikon has given much of a priority to video. Actually, these days it is hard to know what Nikon's priorities are and that makes me pretty uncomfortable as I consider upcoming productions.
The main reason I'm sticking with it so far is that I have a major investment in Nikon lenses. But it has been a year since the D800 has come out and there have been no firmware updates that address video, especially my biggest issues:
1. Shutter Priority mode does nothing in Movie mode. Yes, I'm usually shooting full manual mode, but there are times with run-and-gun situations where I just have don't have the ability to adjust exposure as lighting conditions change quickly. I'm usually preoccupied with focus. As with all of my other video cameras (and with the D800 in Stills mode), I want to lock the shutter speed that corresponds with the frame rate (e.g. 1/60th second for 30fps) and let the camera adjust aperture (or ISO as a last resort) to maintain correct exposure.
2. Although the power aperture feature is really useful to set up the shot, it doesn't work once recording begins.
3. Likewise for audio. Would be great to adjust it once recording begins.
4. Just occasional flakiness which requires me to cycle power to regain control of the settings.
Item #1 is the only issue that has forced me to grab one of my other cameras when I really didn't want to. The issue for me is that I need to see some kind of gesture from Nikon that they are serious about the video capabilities of the D800. I'm keeping my options open, but I am paying close attention to non-Nikon options for future productions. But I'd rather not.