New footage obtained by the Guardian today gives an insight into the way police and protesters treated Ian Tomlinson, the man who collapsed and died shortly after being struck and pushed over by the police at last week's G20 protest.

The video provides further evidence that the initial explanation of Tomlinson's final moments released by police was misleading. It also corroborates the version of events given to the Guardian by witnesses to his death, some of whom are pictured in the film.

Moments before the video was shot, around 7.20pm on 1 April, Tomlinson was struck with a baton and thrown to the floor by a riot officer who had covered half his face with a balaclava and concealed his badge number.

Tomlinson was then seen stumbling down Cornhill, in the City of London, towards the spot, opposite St Michael's Alley, where he collapsed.

The footage, shot by Nabeela Zahir, a 27-year-old freelance journalist from London, contains three important elements to note:

• Police move quickly to push away those protesters and bystanders who were aiding Tomlinson, including a man on the phone to the ambulance service. The ambulance service wanted to be put in contact with the officer, who declined to take the call.

• The reaction of protesters is important. After the demonstration, police accused them of impeding Tomlinson's treatment by subjecting the officers and medics to a hail of missiles. In the video, a missile is seen to be thrown but you can hear someone in the crowd saying: "There's someone hurt. Don't throw anything." This indicates something was thrown, but certainly there was no barrage of missiles on film, and nothing reached the police. A man is also seen, standing with his arms in the air, shouting: "There is someone hurt here. Back the fuck up."

• The riot officers have concealed their faces. Pause at 56 seconds. There are four officers in shot. Three have their face masks pulled half-way up their faces.

• This article was amended on Friday 10 April 2009. The original version said that no missiles were thrown while the camera was rolling. This has been corrected.