Sharon Steenkamp, Reeva's cousin, told the Associated Press that the model and law graduate was "proud of being in the show" and reminded them in their last conversation to make sure that they watched it.
The South African Broadcasting Corporation aired the Tropika Island of Treasure programme, showing the late Steenkamp—the victim of a Valentine's Day shooting at the home of Pistorius, the Olympic star and double-amputee athlete. She is laughing and smiling, and blowing a kiss toward the camera in Jamaica when it was filmed last year.
South Africans also saw her swimming in the ocean and watching people jump off a cliff and into the sea, shaking her head as they leaped.
SABC said it was dedicated to Steenkamp and displayed the words "Reeva Steenkamp 19 August 1983 - 14 February 2013" between images of a rose and a candle in a short tribute before the show aired. She was also seen blowing the kiss as she sat on a Jamaican beach and her name again appeared on screen with the years of her birth and death.
The country was rocked on Thursday when news broke of Steenkamp's shooting death at the upmarket house of the star athlete. Pistorius was arrested and charged with her murder and remains in custody in a police station. His family has strongly denied prosecutors' claims that he murdered her.
Steenkamp's family said earlier on Saturday that it had not been contacted by either the SABC or the show's producers for permission to air it, but were not opposed to it because Reeva had wanted everyone to see it.
"Her last words to us personally were that she wants us to watch it," Sharon Steenkamp said, hours before the programme was shown.
SABC aired the reality show on its main channel, which prominently featured Steenkamp.
The show's executive producer, Samantha Moon, said going ahead with the show "is what she would have wanted".
Steenkamp, a 29-year-old blonde model who graduated from law school, died after suffering four gunshot wounds, police said. Officers recovered a 9mm pistol from Pistorius' house and quickly charged the Olympian with murder for Steenkamp's killing.
Pistorius will appear in court on Tuesday for a bail hearing, something police have said they oppose. Prosecutors also say they will pursue upgraded charges of premeditated murder against him, which means the disabled icon and double-amputee runner could face a life sentence.
Steenkamp was known in South Africa for appearing in commercials and as a bikini-clad model in men's magazines.
Pistorius and Steenkamp met on November 4 at the Kyalami race track, said Justin Divaris, a mutual friend.
Divaris said his own girlfriend was a close friend to Steenkamp. Pistorius and Steenkamp immediately hit it off and decided in the spur of the moment to attend a sports award ceremony together the same night, Divaris said. At the time, Pistorius had been dating another woman and his personal life was constant fodder for gossip pages.
Later, however, problems may have started, as police have said there were previous domestic altercations at Pretorius' home in a gated community near South Africa's capital, Pretoria.
A Steenkamp family spokesperson said late on Friday that relatives still faced a long struggle to come to terms with her killing.
"I can't see the family getting over this shortly," said Reeva's uncle, Mike Steenkamp. "It's going to be a long, long-term reconciliation with a lot of things and issues."
Family members plan for a memorial service on Tuesday for the model in her hometown of Port Elizabeth. Pistorius has a court appearance scheduled in Pretoria on the same day for his lawyers to argue that he can be released on bail.
Portions released earlier on Saturday of the reality show featured Steenkamp laughing and smiling on the beaches of Jamaica. Another portion shows her swimming with two dolphins, which tap her on the cheek with their snouts.
"I think the way that you go out, not just your journey in life, but the way that you go out and the way you make your exit is so important," Steenkamp says in the video. "You either made an impact in a positive or a negative way, but just maintain integrity and maintain class and just remain true to yourself.
"I'm going to miss you all so much and I love you very, very much." - Sapa-AP