I have been using my D7000 to cover my daughter's school band concert and to me it works well. I use an external mic (Nikon ME-1), and shoot manually. M mode, ISO 640 - 1000 (average), f2.8 or whatever fast lens that you have, 1/60. Keep the mic setting in "auto". You can decide the resolution but the 1080p 24fps works very well for me. The camera has 29min 59 sec limit on video so it doesn't really matter if you put a 16mp or higher. Once the 30min limit is reached, simply remove that card and install a new one.
I use a tripod of course and focus manually. If your lens has a M/AF switch, keep it in manual and turn "off" VR. This will also minimize your battery power use. Otherwise the lens might hunt and will create noise which can be recorded in the video.
D7k video rig by
gqtuazon, on Flickr
Here is a sample video that I took with the D7000