I can say from experience...having at one time been a commissioned peace officer...that when you are in a tense, make a quick decision or possibly be shot yourself...you get such tunnel vision that you do not even look at what you pulled. You just pull. That is why many officers, as did I, carry their taser on the opposite hip from where they carry their sidearm. She clearly was carrying them both on the same hip or very near each other. Most of the officers I have ever worked with carry the taser in a different place. Most departments policies are that the taser is to be carried on the opposite side from the offices’ duty weapon. Then when they decide to deploy the taser, they have it in a place where they cannot accidentally pull their duty weapon.
The point is to avoid it escalating to that point. Something it seems most big city cops aren't very good at these days.
From the video, the other two officers were carrying their tasers in crossdraw holsters on their left hips. From that, I suspect that’s department policy. As a result I’m not sure she was carrying both on the same hip/close to each other. I think she just completely screwed up.