No—on the Nikon D90, the video behavior is fixed by the camera’s internal video mode. It either downsamples the sensor data or skips/combines sensor lines to produce 720p, and there’s no user setting to switch it to a true center-crop readout for extra reach.

In practice, that means the sensor’s higher resolution does not give you an in-camera digital zoom option for video on the D90. To change that behavior, Nikon would have needed to add it in firmware, or it would require unofficial hacked firmware. So with the standard camera firmware, the answer is essentially no.