The 16-year-old North Babylon boy, who recorded the Dec. 18 beating of a 13-year-old girl by three other girls, surrendered to police Monday afternoon and was charged with unlawful assembly, Suffolk County police said.
He was released on $100 station house bail and was told to appear in court March 22.
Earlier this month police and a 13-year-old girl on charges of juvenile delinquency and attempted assault in the beating at a high school.
After the incident, a group including the attackers can be seen running away, then laughing and boasting about how easily they overcame the girl. The image turns fuzzy, making it appear as though the person holding the camera is running with the group.
The victim's parents were initially hesitant to press charges, but chose to go ahead when the video gained public attention and was broadcast on several news shows, police said.
On Monday, Suffolk County Executive Steve Levy said he hoped the boy's arrest would send a message to youths.
"I hope this arrest, which we expect to be the final arrest in this case, makes it clear that we are taking this abhorrent behavior very seriously," Levy said in a statement.
He said he hoped young people would get the message "that bullying or physically abusing peers is serious and unacceptable, not entertainment fodder for a Web site."