Sickening security vision has been released of the moment a man was attacked inside a Melbourne nightclub because of his ‘man-bun’.

The video shows Elliot Harvey at a crowded Brunswick venue in May last year.

Just after midnight, a pair of young men – Brent Moresco and Bradley Elmore-Jeffries – are seen surrounding Mr Harvey, before repeatedly punching him.

Brent Moresco and Bradley Elmore-Jeffries have been jailed over the attack on Elliot Harvey (centre). (AAP/9NEWS)

It’s believed Moresco and Elmore-Jeffries had made snide remarks about Mr Harvey’s man-bun hairstyle prior to the assault..

Judge Christopher Ryan today told Victoria’s County Court said after an initial confrontation the victim had thought it appropriate to nudge Moresco, whose "reaction to that slight was one of immediate intimidation and violence".

While Mr Harvey raised his arms and tried to walk away, he was shepherded back to the group where Moresco punched him three or four times, hitting him at least once in the face.

He then stood back while Elmore-Jeffries "threw lots of punches", the court heard.

Judge Ryan said random violence committed by young men drinking alcohol was common.

Moresco, 20, outside court today. (aap)

"It is usually brief and not premeditated but it has a profound and long lasting impact on the victim," he said.

Mr Harvey, an environmental scientist, has felt "pathetic" about his ability to work since the attack, can no longer enjoy sports like surfing and most nights drinks himself to sleep.

Judge Ryan stopped during the sentence to ask if Moresco found his comments amusing. He earlier warned him to keep his hands in his pockets next time he appears on television, referencing his outburst after a previous court appearance that the judge saw on the news.

Moresco, 20, was sentenced to three years in youth detention, while co-accused Elmore-Jeffries, 22, was sentenced to three years in adult jail. He will be eligible for parole after 21 months.

Leaving court after the sentence, Elmore-Jeffries told his family he loved them, while Moresco said: "I'll see you on the other side".