Horror, degradation, disbelief...! I haven't watched any of the posted videos to be honest, but I think I understand the premise of the origional post. I really don't care to watch it. I don't want to get to the point where I consider an atrocity, as just another atrocity.
Are they just different cultures, wearing different uniforms, living in different times, committing the same thing for the same reasons? I don't think so! Lots of reasons over the years, and I see no reason to list them, it seems they're well documented.
Custer and his men were killed in one of the worst American military disasters ever. Would you consider that an atrocity by the combined forces of the Sioux and Cheyenne Indians? Maybe just a little bit of payback? Or were they just defending their village and Custer fucked up?