[Pond, James Pond]

we have no clue of what occured before the video began

Absolutely true.

I don't question the common sense in your comments, but they in themselves are also making suppositions about what happened.

I have put forward some suppositions: they postulate an alternative to how some have interpreted or justified the events, but ultimately can't be the basis for my point of view.

That is why I am doing my best to confine my conclusions based on what I have seen.

I see a guy walking, only walking, when he is tazered by a policeman at his 9 or 8 o'clock.

If we later find out that he had already assaulted someone in the restaurant, then that would be a relevant point to be taken into account.
Until then, though....