Stop Rockets (Halo 3)

Not much of a skill but ohwell. On Halo 3 you can use the gravity hammer to stop rockets before they blow you 100 ft in the air. When rockets are shot at you just press the shoot button with the grav hammer at the right time the rocket will spin off and blow up leaving you a perfect chance to shoot at your opponent. Im pretty sure you can do it with grenades aswell but im not sure so if you get stuck with a plasma grenade dont blame me. P.S do not try this in real life.......as may result in loss of limbs. I found a vid on youtube here is the link http://www.youtube.com/watch?v=DqM7r7WMB44 ( I didnt make this video)