Have you watched the video? It is clear as day that the officer doesn't even touch his pistol until Brooks fires the taser at him.
And the taser itself may not be lethal, but it incapacitates, and gives access to the officers lethal weapon. They're trained to always be one step higher in the force they use. Brooks used less than lethal, the officer uses lethal.
Again, he was not unarmed, he was not innocent, he was not just running away. He used a less than lethal weapon on an officer. It's clear as day if you watch all the angles.
Yep you clearly never watched it. Apparently you can grab a cop's gun while running away from him. ---