Just put the full footage in front of an unbiased third party for a multi-stage verification first. The problem space isn't "is that weird shadow in the picture a gun or not?" it's "does the kid in the video have a gun?". It's not hard to figure out the difference between a bag of chips and a gun based on body language. Presumably the kid ate chips out of the bag? Using certain motions that one makes when doing that? Presumably the kids around him all saw the object in his hands and somehow did not react as if it was a gun? Jeez.
