So I've spent about two and a half years deployed to Iraq, and seen my share of combat. I've served in several different infantry positions, both as a dismount and as a gunner in a Bradley Fighting Vehicle (the "Brad" mentioned in the video).
I am always skeptical of these sorts of videos, because they lack context. As a third party, one never knows the full tactical situation, the histories of individuals and groups in the area, the mission and orders of the soldiers involved. So everything I say must be understood to be the view of a third party observer, one with a fair amount of boots-on-the-ground experience, but a third party nonetheless.
Based solely on what appears in the video, it doesn't look like the gunner(s) had sufficient justification to fire. Simple possession of an AK-47 is legal in Iraq, and having it on the street isn't always enough to warrant immediate termination, and certainly not when the target is standing in a crowd of unarmed personnel. The "RPG" was poorly identified, and didn't appear to be of significant threat to the Crazyhorse element.
It does sound like there had been recent combat in the area, so that may be why there was a minimum standard of ID used prior to engaging the targets. One thing to remember is that Bushmaster element can't always see everything that Crazyhorse does; they rely to some degree on the helos' info to inform their commands.
If nothing else, this looked like a textbook situation for dismounted troops with air cover. It sounds like they had Bradleys and dismounts nearby, and they probably should have been sent in to deal with the situation. Dismounts have an infinitely superior view of what exactly is happening on the ground, and when combined with top-down info from the birds, they can properly assess a situation. If these RPGs and AKs were really cameras as reported by the site, then that would have been obvious to dismounts.
Firing on the van completely blew my mind. This looks like a series of tactical mistakes combined with an overeager air element, combined with total disregard for the normal RoE (and again, I don't know if they were operating on some kind of modified Rules of Engagement).
U.S. soldiers, in my experience, go to great lengths to prevent civilian casualties. Maybe things are different in the air, but those of us working on the ground have to look at everything we do, up close and personal. Don't paint U.S. forces with a broad brush based on the actions and mistakes of a few individuals. Also, remember that it's not the line troops that are performing coverups. Talk to your government about that.