A video has been released by prosecutors showing the alleged shooter who killed 17 people at Marjory Stoneman Douglas High School discussing in a chillingly lighthearted manner his plans for the mass murder the day of the attack.

In the video, the alleged shooter says that “you will all know who my name is” after the shooting. “I’m going to be the next school shooter of 2018. My goal is at least 20 people with an AR-15 and a couple tracer rounds. I think I can get it done,” he says in the video, which shows him describing his plan on what appears to be the morning of the shooting.

“Location is Stoneman Douglas in Parkland, Florida,” he continues. “It’s going to be a big event, and when you see me on the news, you will all know who I am. You’re all going to die. Pew pew pew pew. I can’t wait.”

The video was released by prosecutors Wednesday, and offer a disturbing insight into the shooter’s thought process, and his determination to use violence to get media notoriety.

"Today is the day, the day it all begins," the shooter says in one of the clips. "All the kids in the school will run in fear and hide. From the wrath of my power, they will know who I am."

Fred Guttenberg, whose daughter Jaime was one of the victims in the shooting, told the South Florida Sun Sentinel that he had taken a look at the transcripts, but does not want to watch the video.

“I already know what he did,” Mr Guttenberg told the paper. “He’s evil. Repulsive. He deserves to be dead. … He talked about how he was going to be someone now. It’s a level of thought that I can’t comprehend. It looks, from the words, like the kid had joy. I don’t want to see the delight he took in planning the murders of our children.”

March For Our Lives: Emma Gonzalez's 6 minute and 20 second speech for the Parkland victims

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Andrew Pollack, whose daughter Meadow was killed in the shooting, said the videos take away possibility that the shooter will plead insanity.

“It just shows this kid was competent. This whole thing was premeditated murder,” Mr Pollack told the same paper. “This kid knew exactly what he was doing.”

In the videos — which are not long, and appeared to have been filmed on a cell phone just before the attack — accused shooter Nikolas Cruz, 17, said that he has “had enough being told what to do”, and described a mind set that appears at least in part motivated by revenge for previous encounters with fellow students at the high school.

“Telling me I’m an idiot and a dumbass,” he says in the video. “In real life, you’re all the dumba**. You’re all stupid and brainwashed.”