Re the lack of reaction from the driver of the vehicle.
I was working with a company in the defence sector this week, the group including some ex forces officers.
Their view was that he was probably battle hardened and reacted calmly, e.g. he stopped his vehicle and reversed away from the impending crash, then took control and blocked the road with hs vehicle.
As to saying very little, it appears he was a K9 handler (thus the need to calm the dog) and apparently they are trained to be restrained when with their charge.
The video is one of the most sickening things I’ve seen for a long time and may they all rest in peace.