Snap Aiming Question

[Jughead Jones]

In the following video:

http://www.youtube.com/watch?v=kYVtbvtQoEw

This gent can quickly snap in and out of his aiming view.

What is the control setting for this?

The only one I found is Control Option: ==> Category: View ==> Event: Lean to Gunsight.

While this does the job it is a slow pull to and away the gunsight and still allows my trackIR to muck up my aiming sending the reticle everywhere, while on this vid the gent has a very steady aim on the target.

Thank you for any input.