The D4 has the capability to shoot full HD movies. The technical specifications listed for movies for the D4 are as follows:
HD 1,920x1,080 / 30 fps
HD 1,920x1,080 / 24 fps
HD 1,280x720 / 30 fps
HD 1,280x720 / 60 fps
The D3x does not have the capability to record movies.
The best way to compare the D4 with the D3x is to use the compare tool on our Nikonusa.com. Go to the below page, check the "Compare" boxes below each camera then click "Compare Now" to see the specifications for the selected cameras side-by-side.http://www.nikonusa.com/en/Nikon-Pr...