The guy doing the shooting was trigger happy, but murder is probably too strong for this. Clearly this is a fucked up example of what happens in the midst of urban warfare, but more than that is going beyond the context of the video.
After the shooting, a black van runs up to collect bodies and help the wounded, in a very organized fashion--- it doesn't seem unreasonable that they thought that they were dealing with a team radio'd by insurgents.
I think the bigger problem here is that you have a godlike helicopter raining death on people below, with no on the ground intelligence.
Why doesn't the helicopter have the ability to shoot non-lethal rounds in this kind of situation? Why can't they communicate with the man crawling after the shooting? If we can fly UAVs from Vegas, why can't we fucking drop a remote ground vehicle to deal with grey area situations without killing eight people?
This seems like a disgusting failure of capabilities more than malicious murder.