It shows the Paralympian walking without his prosthetic legs, with his arm held out before him with his fist clenched as if he was holding a gun.
It also shows him carrying a woman – his sister Aimee – from the bathroom in a demonstration of how he carried Steenkamp downstairs.
It was filmed by The Evidence Room, an American company specialising in forensic animation and was aired on Channel Seven’s Sunday Night program.
Pistorius's Lawyer Brian Webber said the “visual mapping” re-enactment was for trial preparation only and had been "obtained illegally."
In a statement reported by the Sydney Morning Herald, he added: “For the family, the airing of this footage constitutes a staggering breach of trust and an invasion of the family’s privacy.”
Sunday Night executive producer Mark Llewellyn said: “We would not have run the footage if we thought we had obtained it illegally.”
One legal expert in Johannesburg, Professor Stephen Tuson of the Wits School of Law, said the screening of the re-enactment footage could be a breach of sub-judice laws that prohibit the publication outside the courtroom of evidence or material that could influence the outcome of the trial.
"If this was done in preparation for the trial in the context of attorney-client confidentiality, it would be privileged and its publication would be a breach of the sub-judice rule. Its consequences could be a reviewable irregularity," Tuson told Reuters.
Pistorius is standing trial for murder in South Africa. He denies the charge, maintaining he mistook Steenkamp for an intruder when he fatally shot her in the early hours of Valentine’s Day 2013.
He faces 25 years in jail if convicted of her premeditated murder.