My hands are shaking, my heart is pounding.  You would think I just stepped off one of the world's tallest free-fall rides.  But I haven't--yet.  I feel this way just from watching the newly released Zumanjaro video made from the rider's point of view.  The ride, which sits inside the Kingda Ka roller coaster at Six Flags Great Adventure in Jackson, N.J. is now open.  So if you were thinking of checking it out, consider this your official virtual-reality test drive.