With the standard firmware for the NxtCam you can't get video from the camera. You can replace the firmware on the NxtCam but it is not a simple programming environment, and even then you will have very low frame rates. The Mindsensors site has details of how to obtain the NxtCam firmware and the tools that you need to re-program it. Take care though it is possible to end up with a non functioning camera! I made public an early version of my custom firmware that allows you to grab frames from the device, the firmware is available here:
http://nxtcam.svn.sourceforge.net/viewv ... loomyandy/The following thread gives some details of the toolchain required (the NxtCam firmware is a mixture of C and ATMega assembler), it also provides some details of the issues encountered when trying to grab images. As you can see when operating in the highest resolution mode (which is not exactly HD), the transfer time is of the order of 20 seconds...
Note that I am not in a position to support this code. Unless you are totally comfortable working with the device at a very low level in embedded C then I would not recommend replacing the standard NxtCam firmware....
Good luck...
Andy