That jives with what the witnesses said. The shooting happened in a blink of an eye. It looks like the text dude jumping up and turning around triggered the defensive reaction.
The video and the prosecution are pointing out that he already had the gun in his hand — he lied when he said he drew it from his pocket.
Which means that he was going to shoot him one way or another and was just looking for an excuse.
The thrown popcorn was the excuse and yet he knows that it’s apathetic excuse and does not mention it in any of his statements to the police.
From that time until today he and his defense still insists there was a UFO — that popcorn was not the reason he fired.