Maybe the video explains it but why did the Millers keep pulling the mattress out of the dumpster?
I've rented dumpsters in the past for contruction projects and it is a real pisser to find that someone has filled up your dumpster with their trash. For one thing, you pay for the dumpster, plus round trip delivery time, emptying fee, and a tonnage fee, maybe $40 to $60 per ton. There is no such thing as a free lunch, and someone is paying for someone else's trash when it's put into an unauthorized dumpster.
Still, it's not worth shooting someone over. Not many things are worth shooting someone over other than life or death situations. The Miller's should have called the sheriff if there was a problem with the dumpster.