Jamie Spendiff's attack on Craig Logie, who was out with friends on a stag night, was captured on CCTV.
Spendiff took part in a further assault on other men with a co-accused after killing the married 36-year-old last August.
Spendiff, 26, was remanded in custody ahead of sentencing in July.
In CCTV footage shown to the High Court in Edinburgh, Mr Logie could be seen lying motionless on the ground after the assault.
Advocate depute Andrew Brown QC told the court: "Witnesses speak to hearing the sound of a crack as the deceased's head hit the ground and he did not move thereafter."
The construction manager suffered a brain injury and fracture to the back of his head following the attack at Friars Street on 7 August.
Spendiff, of Cullercoats, North Tyneside, admitted assaulting and killing Mr Logie by punching him on the head causing him to fall to the ground where he struck his head.
He also pled guilty to committing a breach of the peace along with Shaun McCarthy by conducting themselves in a disorderly manner and fighting with others.
Both also pled guilty to assaulting Paul Stubberfield and Stuart McKee in a taxi in Friars Street.
The court heard that Spendiff and McCarthy had gone out drinking for the evening after working together as technicians on wind turbines.
Mr Brown said that everyone appeared to be in good spirits, but a member of the stag party and another drinker then became involved in a heated argument.
After patrons left the pub, a general melee broke out which ended with the fatal blow to Mr Logie.
Mr Brown said: "Spendiff punched the deceased, who again had his arms up and out to the side, once on the face with force causing him to collapse to the ground.
"He swung another punch at the deceased as he fell but missed.
"With the deceased now on the ground Spendiff initially moved away before returning and danced round the deceased, at all times being moved away by the accused McCarthy and at one stage a female passer-by."
Mark Stewart QC, for Spendiff, said the killer had expressed his sorrow for the victim and his family.
Judge Lady Stacey remanded both accused in custody, saying the culpable homicide charge had "led to tragic consequences and a man has lost his life".
A man danced around his fallen victim after delivering a fatal blow during a street attack in Stirling, a court heard.