Lol, pretty clearly some one sprinting in the crowd. Cameras don't pick up everything, especially things in the distance, not in focus and going into a cluster of the same colour. The way the camera sees it is one black blob going into a large black blob, it's easier for the camera to just ignore the addition of another black blob.
https://www.youtube.com/watch?v=T2COq-n-_YA
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It is just someone running.