The problem here is that Wikileaks' edited version of the video doesn't let the facts stand for themselves. Instead they applied their own political agenda in order to influence the viewer's opinion.
Here are some of the *facts* that Wikileaks excludes in order to (IMO) purposely distort the viewer's impression to make this appear to be a clear-cut case of wrongdoing:
Fact #1) There were firefights ongoing in the immediate area where this took place. U.S. troops on the ground there had called the helicopters in for assistance. The ground troops identified this group of men as being armed and as being a threat (apparently believing they had been participants in earlier firefights).
Fact #2) Some of the men in the group *were* armed. They were carrying *at least* one AK-47 rifle and one RPG. They are clearly visible in the unedited video (They may also be visible in the edited version. I don't remember seeing them, but the video's editing may have simply drawn my attention away from them). They were recovered by the infantry who arrived on the scene after the attack. The RPG rounds were apparently later destroyed by explosives ordinance disposal personnel (i.e. "The Hurt Locker" guys).
Fact #3) The photographer peeked around the corner, pointed his camera at U.S. troops and vehicles down the street, and snapped at least three photographs of them. It's not clear in the video that this is what's happening; it became evident after the fact (when the camera was recovered). The helicopter crew saw this and mistook it as an attempt to target the U.S. troops and/or vehicles down the street. This is understandable from watching the video. It's not at all apparent that this person is a photographer. What the crew *did* see was a man definitely carrying an RPG disappear behind that building. Later they see someone carefully peeking around the corner aiming something at the position where the ground troops are.
Fact #4) The U.S. Army didn't cover this up. Reports were written up and investigations were done. They even apparently screened the gun camera video to some members of the press (I believe they can't publicly release unredacted video like this because it would violate the Geneva Convention regarding broadcasting images/video of wounded/killed enemies).
The other thing to keep in mind is that for most of us civilians, the men who were attacked look just like a bunch of regular guys. They don't look like enemy combatants to us. But to a soldier who has been in dozens of engagements with insurgents, these guys would look *exactly* like enemy combatants. They don't wear uniforms. They don't drive armored vehicles. They wear regular clothes and drive around in sedans, and pickup trucks. Perhaps the only ways insurgents can be distinguished from innocent civilians is that insurgents hang around an active combat zone while innocent civilians will generally try to make themselves scarce (notice in the video that the streets are empty, with the exception of this group of men), and insurgents can sometimes be spotted carrying weapons (as was the case here).
Wikileaks would have us believe that it was wrong for the helicopter to engage these men under these circumstances. I think any reasonable person who has even the slightest understanding of war would see that there was a (reaonable) perceived threat and that they took the appropriate action (i.e. they eliminated the perceived threat). Also, they used the most proportionate force they had at their disposal (the 30-mm gun). Wikileaks decries the usage of such an anti-vehicle weapon against personnel, but it's the smallest caliber weapon the helicopter has (the other option would have been a hellfire missile).
As for the van the picture is a little less clear. The helicopter crew did previously observe what looked like it could have been the same van prior to the attack. It's at the very beginning of the unedited video. There's not enough context to know exactly why they seemed suspicious of the van, but the impression it leaves is that someone else (probably on the ground) had notified them to be on the lookout for such a vehicle. Or it may have simply been suspicious because it was driving around an area where active hostilities were taking place. We may never know. Nevertheless, apparently the law of war and the U.S. Army's rules of engagement allow for attacking combatants who are attempting to flee. I'm not necessarily condoning the attack on the van, but I don't think it's a clear-cut case where something illegal was done. Keep in mind that civilians probably do not usually charge into an area where there are quite obviously active hostilities taking place. Consider if the van had been an armored vehicle. Would it have been wrong to attack it? Probably not. But we know that insurgents don't drive armored vehicles so the reality on the ground in this war would never be that easy to discern.
Wikileaks does a good job of making it appear as though "C'mon! Let me shoot!" is merely the gunner's plea to get his adrenaline fix for the day. When viewed in context and with a bit of critical thinking applied, it becomes apparent that the gunner actually is pleading for permission to engage not because he wants to kill for killing's sake, but because he knows his fellow soldiers' lives could be on the line and he is in the unique position to be able to prevent the enemy from being able to even attempt to cause them any harm.
The other thing the video shows us is that war really is hell. We hear that all the time. Well, here it is front and center. To quote a marine I once heard talk about this sort of thing, "We're not trained to come over here and shoot rainbows out of our asses. We're trained to fucking kill people!" While this isn't a pleasant reality for us to have to face, some people obviously have a much harder time dealing with that reality than others.
Links to references:
Interview of reporter who was in the area that day
Unedited gun camera video
Photos from the dead cameraman's camera, the U.S. Army's report, and more