What is the documentary on alien arrival where it mainly deals with humanity's response. The show depicts alien spaceship which has light sails for propulsion. The aliens have not arrived yet but humans have spotted its ship while its on its way to earth and the documentary is trying to show what could be the various reaction on earth. The last scene shows a son reaching his father's home, who is a old man waiting with a gun anticipating trouble due to alien arrival. It was on YouTube and is at least 3 years old, maybe more?