"There are weapons visible at various points in the video and an RPG was found at the scene, these people were not all unarmed."

The official military statement about the incident was as follows:

"The Apache crew fired because militants 'were endangering the stability of Iraq' and because they had positive identification that the militants 'had weapons and were using them against coalition and Iraqi security forces.'"

There aren't any coalition or Iraqi security forces in the area, and none are ever mentioned in the video. So while it's possible that an RPG was found at the scene, it's just as possible that the military was lying about both.