The Russian Santa was energetically performing and running around with the youngsters before footage captured him coming to a stop and falling backwards.
As the confused youngsters run towards him, they can be heard giggling as they think his tragic collapse is part of the festive game.
But the actor playing Santa, named as Valery Titenko had tragically suffered a sudden and fatal heart attack.
Another cast member, a woman dressed as a clown, is seen rushing behind the tree to help the stricken 67-year-old.
As kindergarten staff confronted the young students, he was rushed to hospital in Kemerovo but died on the way, said a medical source.
The man named as Valery Titenko, 67, a well-known professional actor in the city, 2,230 miles east of Moscow.
It was revealed today that he had not been feeling well, and had complained of chest pains, but did not want to let the children down so came to perform for them.
A spokesman at the Musical Theatre of Kuzbass where he was a star said: “In recent years his health was not ideal.
“He had been through complicated heart surgery, but still performed on the stage and had been working at full capacity, not sparing himself.”
He had been given a day off from the theatre but insisted on attending the children’s festive party in Siberia.
“The man felt ill in the kindergarten,” said a medical source.
“He was taken in an ambulance but died on the way to the hospital.”