War means high-stakes decision-making using low-quality information by agents who are human and therefore fallible. War means chaos and brutality and unjust death on a grand scale. When you vote for war, this is what you get, no matter how good your intentions. It happens every day in every war. The only difference here is that it was caught on camera and released.
So what did Assange achieve by releasing this video? We already knew war is bad. The existence of the video just evidences that the US military is good at record-keeping, which if anything points to an institution that cares about the actions of its soldiers and is capable, in principle, of holding them to account, rather than just unleashing men with guns to do random unsupervised violence, which is what war looks like in many corners of the world.
The people to get angry with are the politicians and media pundits who who rush other peoples’ kids to war for trumped up jingoistic reasons, not the kids who inevitably fuck up the operation on the ground.