The shocking footage shows a group of men surrounding a Fiat Punto, in which Aqib Mazhar was travelling with a friend, before attacking Aqib and his friend with metal bars and knives.
In the video, the killer can be seen opening the rear passenger door and stabbing Aqib before running off.
Aqib was rushed to the Queen's Medical Centre in Nottingham but died a short time later.
The attack took place on Russell Road, Nottingham, at 8.30pm on June 1, 2016.
Five men - Mohamud Alasow, 20, Junaid Farrukh, 23, Mohammed Qasim, 26, Qamran Ahmed 23 and Hamza Omar Adam, 19 - were jailed for a total of 44 years for manslaughter.
But the man who delivered the fatal blow has not yet been found and officers have released the footage and a plea to the public to help find the killer.
Detective Chief Inspector Rob Severn, who is running the investigation, said: "We have pursued all avenues available to us in order to catch this heartless killer.
"We are asking everyone to watch this video and please contact us if they think they have any information that could lead to identifying him.
"We know that he is probably a young, local man, and is probably part of the group who were jailed."
And City Chief Inspector Donna Lawton said: "This horrific incident highlights the devastating impact that knife crime can have on families and their communities and we really hope that someone comes forward as a result of this appeal.
"Carrying a knife is completely unacceptable and our knife crime team along with every other police officer will keep targeting this issue, removing any weapons they come across and proactively arresting those who possess one."
Crimestoppers announced last week that a £10,000 reward would be on offer for information leading to the arrest and conviction of the person responsible for killing Aqib.
And Aqib's mum Shameem Akhtar has also made an emotional appeal, asking people for help to find her son's killer.
She said: "We have to live our lives without Aqib, knowing that the man who took him away is still out there.
"We are doing this so that someone out there who might have the tiniest bit of information comes forward, as it could be the piece to the puzzle that we need.
"Every day since his death has been agony. He leaves behind two younger sisters, an older brother, a father, and many other family members and friends who cared for him deeply and we just can't put it to rest.
"We want justice done and to be able to sleep at night knowing that this dangerous individual is behind bars."