The attack took place in Summit, New Jersey, and the video was obtained exclusively by Eyewitness News.
New information suggests that at least a dozen young men were present when Williams-Clark and an identified minor allegedly orchestrated the fatal beating of 47-year-old Abelino Mazaniego.
Police say Williams-Clark held a sheet in front of Mazaniego's face while the intoxicated victim sat on a bench. The second teen, who had sat down next to Mazaniego, stood up and punched him twice in the face.
The victim never regained consciousness and died 72 hours later.
Investigators believe Mazaniego was attacked because the teenagers wanted to make a video.
Mazaniego lived in town and had worked as a dishwasher at the local Indian restaurant for three years.
The brutality of the attack left residents stunned.
The county prosecutor's office is still working to identify the person who shot the video, which investigators say was e-mailed to several teenagers in the days that followed the attack.
Anyone with information regarding the attack is urged to contact Homicide Task Force Detective Patrick Bradley at (908) 527-4152 or Summit Police Department Sgt. Michael Rabasca (908) 277-9389.