The footage, aired on the Seven Network's Sunday Night, shows the Olympian describing in graphic detail the events leading up to the moment he shot his girlfriend.
It shows Pistorius moving through a house on his stumps, without his prosthetic legs, demonstrating his claim that he mistook Reeva for an intruder, and killed her accidentally.
The footage has convinced top US forensic investigator Scott Roder that his story is true. Roder was hired by Pistorius' uncle in October 2013 to analyse his version of events.
The digital re-enactment was made by The Evidence Room, which specialises in forensic animation.
But the expose also reveals Reeva's parents and close friends concerns that her relationship was turbulent — even violent.
In the exclusive interview, Roder says he is convinced Pistorius did not mean to kill his girlfriend on the morning of February 14, after weeks of interviewing and analysing the evidence.
"Absolutely, they physical evidence is consistent and his story remains unchanged," Roder told Sunday Night reporter Ross Coulthart.
"If you look at the evidence Oscar's clearly not guilty."
In the revealing vision, the 27-year-old paralympian is shown in a Nike singlet running without his prosthetic legs and pretending to hold a gun out in front of him.
It also shows how he bashed down the bathroom door and, using his sister to demonstrate, how he pulled Reeva from the bathroom and carried her down the stairs.
Roder says Pistorius' unwavering account of his movements that day and the physical evidence has him convinced of the Blade Runner's innocence.
"When he’s on his prosthetics, you know he’s very tall broad-shouldered athletic guy he looks like he can really handle himself," Roder said.
"But when he takes his prosthetics off and he’s on his stumps uh he’s short, the confidence washes away from his face."
At around 3.12am on February the 14th, shots were reported from the athlete's secure compound in Pretoria, South Africa.
At 3.19 Pistorius called a neighbor. At 3.20 he phoned for an ambulance. At 3.21 he called Security at the compound.
Before carrying Reeva downstairs, he went back to the bedroom on his stumps to put on his prosthetics.
"Oscar returns to the bedroom to put on his prosthetic limbs as quickly as he could - 25.61 seconds," Roder said.
Screams were reportedly heard coming from his home, but it remains inconclusive if they were from Reeva or Pistorius.
Neighbours in the gated South African estate also reported hearing several sets of gunshots - the second set Roder claims were made by Pistorius breaking open the toilet door with a cricket bat.
Reeva Steenkamp stopped breathing three minutes before the ambulance arrived and, according to paramedics, died in his arms.
Her parents and friends remain unconvinced of Pistorus' story and insist the couple had a rocky relationship.
"Why? Why did he shoot her? How did she end up with a person like this?" Reeva's mother June Steenkamp says in the emotional interview.
June also revealed the moment she discovered her daughter had been killed.
"I had a phone call at seven in the morning. He said, "There's been an accident. She's been shot." I said "You better tell me now if she's dead or alive."
"He said, "I'm very sorry to tell you but she's dead." And then I phoned Barry."
The unseen footage of Pistorius was filmed in his Uncle's home, but Sunday Night made an exact replica of the top floor of Oscar Pistorius's house where he shot and killed his girlfriend Reeva. The dimensions are absolutely the same and everything, including the furniture, is in the same position as it was when she died.
Phuti Komo, a close friend of Reeva's also reveals in the interview the model was feeling unsure about her relationship with the sports star.
"She felt, she felt I think, "It is a bit too much". I have lost a true friend."
Komo starred with Reeva in South Africa's top rated TV show, Tropika Island of Treasure.
Ian Levitt, a Prosecutor for Reeva's friends says Reeva was cowering behind the toilet door because Pistorius became violent.
"I think he intended to kill her. Four bullets through the door. Four bullets through the door with that special type of ammunition or not, you're gonna kill somebody," Levitt told reporter Steve Pennells.
"She ran to the bathroom, he was enraged and he killed her."
To gauge public opinion, Sunday Night also conducted a live viewer vote as the investigation was presented.
With over 1.1 million votes - the audience was divided nearly 50/50 during the whole show.