I also think it has been done with the slowitdown cheat. Simply because I watched the replay, and the mouse movement was really fast. That indicates on the cheat being used. When you use slowitdown the mouse view works like it allways does, not slower not faster. This means when you watch the replay, the cam movement will be sped up like the stunt is to 25 fps. You can see this by watching the replay, and not moving your mouse. Doing this will give you the origional point of view + in this case the fast mouse movement. Just give up dude.
Oh and I also watched the one where you landed on your back, and you can notice it even more in that one.