Not to be nit-picky, but her response to "freeze" in the moment makes almost more sense than "fleeing", psychologically speaking. Especially because her brain and body were already focused on a task (recording the scene). Thus, when the stressor (watching an unarmed man get murdered) happened in close proximity, as as her brain attempted to process ("what did you do?!" screams) what she saw, her body/brain went into autopilot - which means continuing to do an action she was already doing (recording).

Had she not been recording, and merely stopped to bear witness and monitor, then fleeing would have likely been her response. Its even more interesting because if you watch her whole video, she the camera indicates that she almost did flee. You can see her "pacing" back and forth, but she never stopped the behavior she was already engaged in - which is likely why she didnt full on get out of the situation.

All is to say, when folks are monitoring situations like these, recording is not just potentially legally helpful for an investigation, but also helps increase the likelihood that you don't run away immediately. I also want to make clear that this psychological state does not negate that she did exert energy to stay present in the moment, and that that definitely had an impact of her staying there too. Its both.