I think the loud high-pitched shriek at the end was the train slamming on the brakes. I think the engineer tried to stop because he thought he just killed a guy. It's kind of corroborated by the idiot's hasty exit.
You know, a kid in my hometown did this once. He and some friends ran into a 'Stand By Me' situation as they were crossing a railway bridge. His friends ran but he dove to the ground.
They found his bloodied carcass about a half a kilometre away after something hanging from the bottom of the train hit him and dragged him along with the train.
Boredom and abject poverty BUT access to a video camera creates amazing tomfoolery.
I was waiting for a Looney Tunes/Tex Avery style second train to suddenly show up when he got to his feet.