The motocross competition in Krasnodar Region in the south of Russia was marred by tragedy when the man, seen in the video in a white shirt, appeared to attempt to run across the track just before the bikes came hurtling towards him.
The man entered the track just behind the earth ramp where the riders take off, and the race leader collided with him at full speed as he was airborne.
The competition was abandoned following the accident and the emergency service were called to the scene. However, the victim, 46, had already died of his injuries as several bikes reportedly also struck him.
A shocking video of the accident, filmed by one of the spectators, was widely shared on Russian media on Monday.
Some witnesses told local media that the deceased man was possibly under the influence of alcohol.