Here is the whole video:
https://www.youtube.com/watch?v=E_jFDaXKUbYHere is where things heat up:
https://www.youtube.com/watch?feature=player_detailpage&v=E_jFDaXKUbY&x-yt-ts=1421782837&x-yt-cl=84359240#t=96notice how the officer kept telling the passenger to stop moving around and keep his hands up and visable.
This was as the passenger exited the vehicle

This was as he starting falling to the ground one second later after getting shot.

His hands weren't even up when he got out, and by the time he was falling to the ground it looked like he was either reaching for his heart or to make a hands up motion.
Just because they found one weapon in the car, doesn't mean that was the only one. The passenger was moving around a lot, he could have been fumbling for another weapon such as a knife or another gun under or in between the seat, he could have unbuckling his seat belt or doing both. I doubt the officers knew who the passenger was, until he was identified. However fumbling around like that and flinging the door open implies two things
1): I'm going to kill you
2): I'm going to run away
not
1):I'm going to give you a great big hug
2):I'm going to run home and bake you all a batch of cookies
Unless an officer specifically declares you are under arrest and announces the charges you are supposed to be allowed to not have to listen to them. When they declare you are under arrest and you try to run that is technically resisting, however still not grounds for getting shot. Regarudless people have reinterperted the rule to "Simon says" where simon is the officer and if you loose you get shot.
There is your average every day encounter where you are free to leave any time you want, and there is a detention where you are not free to leave until stated, and there is an arrest. A dention is like an arrest, but it can also lead to an arrest.
For example a driver a is serving around and a cop pulls him over for suspected drunk driving, that is a dention. He then sees opened beer cans all around the car, the drive then fails the sobriety test, so the officers arrests him for driving under the influence.