It's hard to overlook the video capability of todays DSLRs: They have a much bigger sensors than both compact cameras and camcorders, thus they are able to film also in lowlight situations. and they have excellent image stabilization, thus giving you the opportunity of handholding the camera while filming.
But if you ever tried making video with a Nikon DSLR using the autofocus in F-mode (Always activated AF), you've experienced:
So I thought I'd do it another way. I was at a bar one evening, where I was filming (handheld) the jazz band that played.
I set the autofocus in S-mode (Single AF) thus controlling myself, when to focus. I focused from time to time by pressing the shutter release button halfway down as I was pointing in a new direction, and I found that this method was pretty good. Also I set the Nikon D7000 on ISO 800 and f/5.6 thus obtaining a relatively wide DOF (depth of field) (although this doesn't seem to help much in situations when autofocus fails in first attempt).
See for yourself what I achieved. It was my first time using this method, so it's not a perfect video. But for the sake of testing how to tame the autofocus, I am quite satisfied.
By the way: You'll notice that the exposure jumps while I am panning around the table in the beginning of the video. I would recommend setting the AE-L/AF-L button to: "AE-L (hold)", so you can press the button, and the exposure will lock until you press the button again.
You'll also notice that I am struggling a bit with zooming, as the DSLR doesn't have a motor for that purpose.