At least that's a short route. A guy did this LAX > ORD a month or so ago. Several people asked him to turn it off and he insisted he does this all the time and no one complains. I was a few rows up but while disembarking I told the guy "you're a nightmare" and he looked at me kind of stunned at which point I followed with "there is no chance in this world that is the first time a stranger has said something like that to you, get used to it."
I'll see your LAX-ORD and raise you an LAX-IAD redeye. It was a kid playing games and watching movies and according to his parents "he doesn't like earphones" and "don't tell us how to raise our children!".