"OMG Decapitated Head Prank" is a screamer video uploaded to YouTube in 2010 by JAY KARL
The video begins with the cameraman filming the scenery out in the distance. After a while of filming, the man seems panicked and immediately starts running. Much of the view is displayed in blurry vision for some reason. At the railroad tracks, at 1:16 in the video, a chubby man with a knife appears to kill the protagonist as a loud roar can be heard.
NOTE: The following video contains a screamer.