Time to put the nail in the coffin in this conspiracy.
#1 After zooming in a shit ton, there are 3 separate pieces of string/rope holding the rail down that go OVER THE RAIL, making grinding it impossible without catching and dieing. He obviously stood on top of the car and then hopped on the rail while his friend took a picture.
#2 I have the exact same plastic skateboard jumps and can confirm that skis do not slide on them at all. They pretty much stick you in place.
#3 The story makes no sense, he took a picture on a cell phone which obviously has video capability. This is the 21st century jesus christ.
And a slew of other reasons... So Waka_Flocka, NS kindly says Fuck You. Prove me wrong with a video you little bitch.