Please stop with this nonsense. It's bad for society when adults bend over backwards to make excuses for self-centered, disrespectful little runts like this.
He's dancing on a chained off section of earth on a field that doesn't belong to him. Even if he's a completely oblivious moron, at a minimum he knows he's in a place he isn't supposed to be (and only has the sack to be there because of who his brother is).
You're looking for the "meaning behind his action"? He's a self-centered, disrespectful little runt. Maybe it's more malicious than that (I suspect it is the way he stares down at the memorial at the end of the video), but at a minimum it's that much. And that's more than enough to call this clown out.
If some idiot fired a gun in the air to celebrate the 4th of July and love for his country, but then that bullet came down on some poor sap, would you "care more about the meaning behind the action"? Of course not (I hope). Because sometimes the action is just so stupid and/or careless that no "meaning" justifies it.