Robert Dziekanski, 40, of Pieszyce, Poland, arrived at the airport 10 hours earlier on Oct. 14 - his first airplane flight to begin a new life with his mother in western Canada.
Dziekanski began acting erratically after not seeing his mother in the baggage area, a secure area his mother could not enter.
A coroner's inquest has been called and police have launched their own investigation.
Police Cpl. Dale Carr says the video is just one small piece of evidence and investigators are not making the case on that alone.
"There are a number of other witnesses that have an account and we are interested in getting to the bottom of it," Carr said. "We want people to make judgment on the totality of all of the evidence and that will be shared at the inquest."
But Walter Kosteckyj, a lawyer for the Dziekanski's mother, said he hopes the video holds the police accountable for their actions.
The video shot by traveler Paul Pritchard shows Dziekanski lining up chairs, a small wooden table and a clipboard along the doors separating the secure zone from the public waiting area.
The doors open and shut as he builds a barricade. Four police officers later arrive and confront an agitated Dziekanski.
Loud cries of what sound like "polizia," can be heard as the officers are told by someone that the man is behind the door and only speaks Russian.
The officers vault over a railing and walk Dziekanski behind the glass doors. He gestures at his luggage as they appear to be talking to him.
He then throws his hands in the air and walks away, but the officers follow, apparently indicating he should put his hands on the counter of a desk.
Dziekanski stands with his back to the counter and the officers fan around him before they use a Taser stun gun on him and he falls, screaming in pain.
A voice is heard yelling, "Hit him again, hit him again."
The four officers clamber on top of him, restraining his arms and his head, as Dziekanski twitches. Finally, he is still.