Merseyside Police revealed the shooter used two guns in the attack that killed the nine-year-old.
Olivia was hit in the chest as her mother Cheryl Korbel tried to stop the gunman from entering their home in Dovecot, Liverpool, on 22 August.
Ms Korbel was also injured, as was convicted drug dealer Joseph Nee, who was the intended target of the attack.
Speaking as the footage was released, Det Ch Supt Mark Kameen warned those who were "shielding" the culprit that officers would do "everything legitimately possible" to bring them to justice.
"It is beyond comprehension how anyone can protect a person who is responsible for killing a nine-year-old little girl," he added.
In a press conference earlier, Det Ch Supt Kameen issued a direct plea to those who may have been asked to hide or dispose of the guns.
"I understand you may be frightened of contacting us, but I want you to do the right thing for Olivia and tell us where they are right now," he said.
"If you are hiding the guns and you have no intention of telling us, then I place you in the same category as the vile man responsible for the [killing].
"And we will hunt you too."
He said the gunman was wearing a black padded jacket, a black balaclava with a peak and black gloves, and he was described as about 5ft 7in (1.7m), with a slim build.
"This is the man we are hunting for - we need to know where he went that night or did you see him in the area?" he said.
"This man is toxic.
"He is toxic to our communities and if you are protecting him, he is toxic to you and your family."
He said the video had been released because people may recognise what the gunman was wearing when he "callously ran away from Olivia's house".
"This footage shows the gunman running along Finch Lane away from Kingsheath Avenue," he added.
"You then see him turn right into Berryford Road and go out of sight.
"We know he is climbing into and through people's gardens to avoid being seen."
Det Ch Supt Kameen said police were also releasing footage of a man who was in the area at the time of the shooting who they wanted to trace.
"I'm interested in speaking to him as he may have information that is important to the inquiry by virtue of the fact he was in the area at the right time," he said.
Ten days on from Olivia's death, a collection of flowers, balloons and messages have continued to grow near the scene.
Earlier, Ms Korbel, who is still receiving treatment for her injuries, and other family members visited the site to read the tributes left in the schoolgirl's memory.
During the opening of Olivia's inquest on Tuesday, Liverpool Senior Coroner Andre Rebello said armed response officers found her with a gunshot wound to her chest.
He said a police officer had "scooped" up Olivia and ran with her to try to save her life, pressing his hand on her wound as she was taken to Alder Hey Children's Hospital in the back of a police car.
However, despite the efforts of medical teams, she was pronounced dead at about 23:25 BST.
A post-mortem examination found the cause of her death was a gunshot wound to the chest.
Adjourning the inquest to 4 January, the coroner released Olivia's body to her family for burial.
A 36-year-old man from Huyton and a 33-year-old from Dovecot were arrested on suspicion of murder and two counts of attempted murder in relation to Olivia's death in the days after the shooting and have since been released on bail.
Watch: CCTV shows gunman fleeing after Olivia Pratt-Korbel shooting