Meh, this guy isn't very great at analysis.
He says the guy's coat just isn't long enough to be hiding anything under, even though we can't really see the bottom of it. Fine - I disagree, I for one think that coat is plenty long enough, especially if the gun has a folding stock. But my opinion aside, like, the guy's arm is up and he is clearly holding/hiding something inside his jacket as he's walking into that room. So if it's not the gun, what does he think the guy is holding?
Secondly, none of the cops present except for the one he draws a green check on, is even looking in the direction of the guy when he runs out. So of course green-check-cop is the first and only one who reacts. But as soon as he does, everyone else does react and they don't "just scatter and look confused", they all move to some kind of cover and draw and point their weapons directly at the bad guy.
Third, even the first cop who draws might seem to have a good bead on the bad guy, but almost for the entire time frame this video covers there are people on the other side of the bad guy from him, meaning that obviously he can't shoot, or at least he shouldn't. I guess it's possible that he tried at least once or twice but if he did, it's equally possible that he's the one who shot the other cop who was hit in the vest.
I also don't think it's really that mysterious why the first, low-res version that was released only hours after the incident is so bad. It was taken by someone's cell phone pointed at a security monitor, and that person probably upscaled it using whatever slop tool Apple foists on its users. Releasing it was maybe a bad call, but chances are it was an administration official who felt pressured to deliver *something* to push back against the public clamoring that the whole incident was faked. I think this new video is directly sourced and probably not altered, because I haven't seen generative AI get a running on-screen timestamp right yet.