When the D4s was announced, it was mentioned that the camera could shoot slightly faster than its predecessor. But that extra one frame per second isn’t the only change Nikon made to the D4’s shutter mechanism. The D4s also features a new mirror balancer and damping mechanism that reduces bounce when the camera is firing away at 11 fps.
That feature is demonstrated in the video above, which was put together by Nikon Europe using the Nikon 1 V2. With the V2, they were able to capture 1200fps video of the D4 and D4s shooting at full speed, and then place those videos side by side so you can see how much more stable the D4s mechanism is.