scale of dumb stunts. >> a mountain biker pays the price for trying to pass the buck. october 2011, a 38 kilometer bike race begins across albert falls game reserve in south africa. six kol lom kilometers in, there's a clearing. lead biker spots an antelope to his right. >> he says, hey, there's a buck. and then goes back to riding. all of a sudden, the buck is like, oh, are you challenging me? >> seconds later -- >> whoa! >> he just comes out of nowhere and smashes this guy off his bike. >> almost looks like the buck grabs the biker, throws him down and it's just this massive crash of body and bike.