The clip shows Joshua McLean, 31, walking with friends along Bethnal Green Road on August 6, 2024.
He was found an hour later by medics with a gunshot wound in the chest in Weavers Fields around 8.30pm. He died at the scene.
One year on from his death, a £20,000 reward is being offered for information.
Detectives want to heard from anyone who was around the ‘jungle’ area of Weavers Fields on August 6 or were leaving Bethnal Green Tube station and saw anything suspicious.
They believe there are people who know who killed Joshue but have not yet come forward due to fear of consequences.
The reward is being offered by independent charity Crimestoppers for information that leads to the identification and prosecution of those responsible.
Detective Inspector Jonny Newell, from the Met’s Specialist Crime Command, said: “Although a year has passed since the senseless murder of Joshua McLean, the impact of the day is fresh for his heartbroken family.
“We remain committed to finding those involved in his death, and will be distributing leaflets in the local area to encourage anyone with information to come forward as a matter of urgency.
“If you were in the vicinity of Weavers Field on the day of the shooting, or know anything that could help us, please contact us via 101 quoting 7454/06AUG24. 
Alternatively, you can contact the Major incident Room on 0208 358 1010.
“All information is met with the strictest of confidence and witnesses will be supported by specially-trained officers throughout.”
Those sharing information who wish to remain anonymous can contact Crimestoppers on 0800 555 111 or via their website.
Alexa Loukas, London Regional Manager for Crimestoppers said: “This was a shocking act of violence carried out in broad daylight in a busy public park which led to the tragic loss of Joshua’s life.
“We know there were people in and around the area at the time of the shooting who may have seen or heard something crucial.
“Despite repeated appeals, we believe fear of reprisals has prevented witnesses from coming forward.
“The charity Crimestoppers is offering a reward of up to £20,000 to encourage anyone with information to speak up anonymously.
“You won’t be asked for your name, and we can’t trace your call or identify your telephone number or IP address if you contact us via our website.
“Joshua’s family are devastated and deserve answers.
“Your information could make all the difference.”
