Authorities said it was all to see how fast city police would react to a mock terrorist act.
Michael D. Turley was arrested Monday, nearly two months after the bizarre film was posted to Google Inc.'s YouTube site. He posted $5,000 bond and was released.
In the film, the narrator who police identified as Turley, said he wanted to see how long it took authorities to respond. The introduction to the video mentions the July 20 theater shooting in Aurora, Colo., that killed 12.
"Given this event, I wanted to run a little test here in Phoenix, Arizona," Turley said. "I want to find out how safe I really am, and I want to know the response time of the Phoenix police department."
The YouTube clip showed the masked teen marching back and forth at an intersection with the rocket-propelled grenade launcher on his shoulder.
The first officer found Turley and the teen in a neighborhood, standing in Turley's driveway.
The officer calmly told the boy to put down the weapon and Turley to put down the camera. He didn't draw his gun.
Officer James Holmes, a police spokesman, said Turley told the officer they were just filming a movie, and the officer took down their names and left.
After interviewing people who called 911 and later seeing the video posted on YouTube, police arrested Turley.
"It surprised us that he actually put that video on YouTube," Holmes said.
The police response took just over three minutes from the first call, and a helicopter and SWAT team was dispatched as backup, Holmes said.
Turley, 39, doesn't have a listed phone number. He didn't immediately respond to messages sent Wednesday through the YouTube account.
Police said Turley was charged with creating a false impression of a terrorist act, endangerment, contributing to the delinquency of a minor and misconduct involving simulated explosives.
Holmes said police are recommending charges of endangerment and knowingly giving a false impression of a terrorist act for a juvenile court to decide whether to file against the teen, whose name was not released because he is a minor.