An eight-minute video taken on Burakov's phone by one of his friends shows the two men being fitted into harnesses inside the zorb, which consists of two polyurethane balls with a layer of air between them. The zorb is then released to roll down the hill, the two men spinning inside.
But the zorb is shown bouncing off the intended path, and a man waiting for it at the bottom of the hill tries in vain to catch the ball before it pops over a rocky ledge and disappears down a gorge below Mount Mussa-Achitara.
The person filming the video is heard swearing and asking, "What's down there?" The answer from someone off camera: "It's a catastrophe down there."
The Emergencies Ministry said both men were ejected from the zorb as it tumbled and they landed on the snow about 30 feet apart after having rolled about a mile. Still conscious and able to stand, they were rescued by two skiers, who then pulled both men up to the top of the hill. Burakov suffered serious spinal injuries and died on the way to the hospital. Shcherbakov suffered a concussion and other injuries and remains hospitalized.
Sergei Loginov, deputy director of Z-orb.ru, the largest supplier of zorbs in Russia, said the zorbing run that killed Burakov was in violation of all safety rules. Zorbing requires a groomed gentle slope with fences on both sides of the track and a secure spot at the bottom where the ball can be safely brought to rest, he said, but none of this was present at Dombai.
"It's not even irresponsibility," Loginov said.
The sport of zorbing originated in the 1990s in New Zealand and is now done around the world, most often on grassy slopes. Loginov said there were several zorbing spots on the outskirts of Moscow and dozens more around the country.
Zorbs have been adopted as a symbol of the 2014 Winter Olympics, which Russia is holding in Sochi.