I watched this a couple days ago and as an officer of 30 yrs experience here is my take based on what is contained in the video. This scenario in 99 out of 100 times could be played out with no one dying. I thought it was horribly handled at the end and because they screwed it up, the man died. The shooting, in my opinion, was not justified. There were so many alternatives before deadly force it is very sad to watch.
The Feds have been called in to review the shooting. My guess is tactics will be identified as horrible. They will go into a lengthy dissection of the event. But the shooting itself which is what will be the main focus, may be ruled justified. They will be required to focus on what was happening at the time deadly force was used. Not what brought them there. He had two knives, he had taken a defensive/aggressive posture. The decision to fire was likely made at that moment and before the brain could register the subjects moving to turn the finger was pulling the trigger. While I think the shooting was uneccessary because I have the luxury of watching the video, they will focus on what the mindset of the officer was at the moment deadly force was deployed. I could see it going either way but that doesn't change the fact in my mind, it was a needless and unjustified shooting.