The painter and decorator appeared in Downing Centre District Court to hear the judges sentence, and walked away with a smile on his face after being given the reduced sentence.
Butler, who wrote a letter to the judge claiming he has 'not drunk alcohol in the last 12 months, not even on Anzac Day,' left court with his mother.
Caught on a GoPro video in 2015 in a horrific 17-minute assault showing an intellectually disabled teenaged on a bed as men say, 'She will do us one by one,' and 'next, next, next.'
The victim, who at times during the filmed assaults appears to be comatose, has the verbal skills of an eight-and-a-half-year-old girl.
Butler's presence in the rape room, seated in a chair by the bed as others had sex with the girl, came to light when 'an enhanced version of the GoPro video revealed another person in the room,' the court heard.
The video also contains comments like, 'are you ready for the next one' and 'just bend her over the bed'.
Butler pleaded guilty in July of this year to one count of concealing the indictable offence of aggravated sexual assault.
In his pleading letter to Judge Sharron Norton, Butler asked for a lenient sentence as he had 'done some thinking about his life' over the nine months he had spent in prison before his release on bail.
Judge Norton stated Butler's letter to her regarding the incident 'doesn't actually apologise to the victim.'
Butler is one of seven men convicted and over the rape of the 16-year-old girl.
This article originally appeared on New Idea.