Recently I used the Nikon D7000 in a long format interview setting and was a bit concerned about battery life in video mode. There's not a lot of data that mentions the actual battery life for filming. During my interview shoot the battery went about 1.5 hours continuously before indicating "low battery" in the camera display. I'm not sure how much longer it would have gone, but I swapped out the battery and through that one on the charger for good measure. If you're shooting a project with the D7000 I would highly suggest at least one spare battery, or even two for insurance depending on you're power availability and length of shoot, etc.
The Nikon D7000 uses the EN-EL15 Nikon battery.