Tomlinson, who had his hands in his pockets and is seen offering no resistance at the time, was flung to the ground, after which bystanders came to his assistance.
Within minutes he had collapsed in a nearby road suffering a heart attack. Police attempted to resuscitate him and he was taken by ambulance to hospital where he was pronounced dead.
The IPCC is now attempting to obtain a copy of the video to determine whether the action by police contributed to the cardiac arrest.
Immediately after the death, police said that they had tried to resuscitate Tomlinson but made no mention of any earlier contact.
Scotland Yard have not been able to comment on the footage due to the IPCC's investigation.
The video was shot by an American fund manager who was witnessing the protests out of curiosity.
About 4,000 anti-capitalist protesters had massed in central London the day before the G20 summit, during which world leaders discussed resolutions to the world economic crisis.
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