Footage shows Pistorius 're-enacting' shooting
Australia's Channel 7 is due to broadcast a documentary on the footage later today.
Australia's Channel 7 has released snippets of the footage in a promotional video for a documentary due to be broadcast today.
The source of the footage has not yet been confirmed.
The 'Blade Runner' says he shot the model by accident, while the state maintains it was a case of premeditated murder.
The Paralympian is also facing two separate firearm-related charges and one for the illegal possession of ammunition.
The video shows Pistorius acting out the sequence of events in front of the camera without his prostheses - from storming the threat to pulling Steenkamp's body from the toilet cubicle.
With his right hand up in front of him as if holding a firearm, Pistorius quickly moves towards the camera on his stumps.
He appears far more mobile without his prosthetic legs than his defence team and expert witnesses have led the court to believe.
Later, Pistorius is seen walking backwards without the need to lean against anything to balance himself.
This latest development raises the question why the video was not shown in court.