From their point of view they are in a helicopter, scared, and afraid that someone is going to shoot a RPG at them. You can't seriously expect them to notice the kids or the difference between a camera and a weapon.
Sure they jumped the gun, they killed innocent civilians, but it was a product of the environment and training they received. It happened because America made those kids soldiers and put them in that situation, with a deadly weapon to control. Don't blame them personally.
What does need to be blamed, on the other hand, is the fact that this video was kept secret and that the world was lied to.
That is disgusting.