Tales Soares, 26, fell on the catwalk at Sao Paolo Fashion Week in Brazil on Saturday night, in what guests initially thought was part of his act.
But the chilling reality of what happened became apparent when medical staff rushed onto the stage.
Footage shown above sees Tales walking seemingly without any problems just moments before he collapses.
Another distressing clip – which Daily Star Online has chosen not to reveal – shows Tales falling face-first on the ground after staggering down the catwalk.
The model was rushed to Accident and Emergency but couldn’t be revived and was later pronounced dead.
It was first thought that Mr Soares had suffered an epileptic fit due to the appearance of foam at his mouth.
But his agent – Rogerico Campaneli – has now revealed doctors believe he may have had a “congenital problem”.
No further information was given, but Tales’ sister told Brazilian media outlet G1 that she was unaware of him suffering any health problems.
“Me and my mother (Heloisa) spoke to Tales by video call before the parade and he said he was well and said he had just finished eating a carrot,” she said.
“We’re very scared and devastated by what happened.
“He was very healthy, ate healthily and exercised every day. He did cross fit and yoga.”
MGT Base Agency – who Tales worked for – said that Mr Soares had never “presented or complained about health problems”.
“We emphasise that Tales never presented or complained about health problems,” they said in a statement.
“He had a healthy diet (he was a vegetarian), did not use illicit substances and was considered in full healthy condition to participate in the parade.
“We await the medical report and we ask for respect at that moment of deep sadness. He will be forever in our hearts and memory,” they added.