This killing happened in front of, and in near proximity to, an innocent woman and a toddler.
You will hear Castile say very calmly that he had a firearm.
When Yanez tells him "Don't reach for it...", Castile calmly says, "I'm NOT reaching for it."
Little did he know he was about to be murdered. Yanez experienced TERROR at the thought of a mere mortal, a mere mundane, a mere "civilian", being in possession of a firearm in his presence.
Yanez' panic and extreme emotional state justified the killing of a citizen who's crime was a broken tail light.
Remember, this is how our police are trained. Anyone and everyone is out to kill them. That is their attitude. Any posture on the part of the citizen which does not resemble groveling, obeisance, and prostration, may very well get him killed.
They tell each other, "Don't worry, bud... we got yer back!"
They are proud of themselves.
Here it is.