You can see him looking at her more than once. At one point he is just staring at her. Now, as a guy, I admit she would catch my eye as well. It looks like there are several people with cameras taking photos and likely reporters in the crowd, but clearly his focus is on her. He only stares at her, glancing past other people to directly look at her more than once. Hey, she is a beautiful woman, and she does stand out in a crowd. 

He's got absolutely no cause to pull the trigger on her. There is no threat. She has been looked over by him more than once, she is quite obviously just reporting, nobody is within 50 feet of the cop. The situation appears completely in hand, there is no violence taking place. Nobody is setting anything on fire. Nobody is breaking windows, nothing, it appears people are just moving peacefully down the street. It is not a "war zone" or even close. 

I think he is obsessing over her, pulls the trigger a bit too quick and that's why the shot is low, and he can't help himself from shooting at her. You can absolutely tell in the video, all he is focused on in the midst of what is taking place is the beautiful blonde. 

I mean, to me, it seems obvious. The guy is a creep and shooting her is the only interaction he is capable of.