Nothing, literally nothing is worse than being crammed into the middle seat of an airplane between two armrest hogs. All you want is to arrive at your destination safely and the dude next to you has made it his mission to invade your personal space for the duration of the flight. Your only saving grace as a middle-seater is the possibility of sleep, but without any armrests, you're left with nothing but three inches of space in front of you while the guys next to you get a window, wall, or entire aisle all to themselves.
Since the middle-seat life is so damn hard, this guy felt warranted in his calling out of another man's lack of plane etiquette. This hero isn't going to let this infraction fly - literally. That's when he conjures up some epic revenge and films the entire interaction.