The few seconds of video shows a man (with back to camera) approach the officer and make a move as though reaching for something in his waistband. When the officer drew his weapon apparently in response the man ran away.. at that time the officer put his gun back in the holster. That's what some are reporting.
I can watch the video and dispute that account.. maybe. But I have no reason to doubt the account even if there were two other officers in the scene. IOW the officer felt threatened.
Watch the full video. You can see him running onto the scene, with at least one other officer. You then see the other officer talking to people at the scene, for several minutes.
I know LEOs who keep their weapons in the middle of their backs. They draw from that area.