Oh don't get me wrong, I would absolutely not want to claim that I would act differently, let alone better, if that is even a notion. I've never been in such a situation, impossible to pretend to know what it's like. It just strikes me when watching, right at the beginning.
It's also not the first time this kind of thing strikes me, there was a similar situation in one of the videos of the assault on the Capitol, where one cameraperson was filming a security officer all alone keeping in check intruders in a precarious situation, slowly retreating, and the person filming was keeping their distance and filming like a cameraman. Thought it odd they would be so taken up with recording that they seemingly don't even think about getting involved.
It really is just a very speculative, and maybe not fully appropriate or frivolous given the occasion, aside, but the omnipresent and routine use of cellphone cameras to capture surrounding events on video surely has somewhat influenced and transformed our very relation and attitude to the situational reality we're in. But it also obviously has enormous merits for evidencing, as you point out.