The video provides motive. Although the LEO might not have known about the robbery, certainly Brown did, and would likely respond accordingly, thinking he was about to be arrested for assault.
It would provide a logical explanation of why Brown seemed to go into the situation brawling... he had not just a chip on his shoulder, he had the entire Frito-Lay factory. As did the community which rioted, burned, and looted.
A cooler headed Brown might have just dashed away from the police car, into the crowd. But pride goes before destruction, and a haughty spirit before a fall.
Bingo.