Are we watching the same video? He clearly shoots her. He is aimed at her and shoots her. Plus, wasn't she shot in the chest, not the neck so the shot angle is fine? I really don't think you can say that's a .45 Glock just from the shitty video. And even if it was, expecting some kind of movie effect sending her body flying back with a load of gore and blood is absolute nonsense, even with a .45. Depending on where exactly she is hit, it could take a moment for blood to fill up whatever cavity space the bullet entered before spilling out of the entry hole. In the other videos you can clearly see her respiratory system is compromised with blood coming out of her nose and mouth.

As for the inaction of the tactical police coming up behind her, they arrive after she's been shot hence not stopping her. Look at their confusion, pointing guns through the barrier before realizing the shooter isn't a threat to them. After that they're just trying to work out how to deal with the situation. I imagine their primary concern isn't administering first aid to her but securing the immediate area in case they're jumped/someone in the crowd opens up on them.