Police say Kelly was involved in a gruesome incident Friday near Union Square shortly before 5:00 p.m. and was caught on camera.
Jenny Shao recorded the video that's now being used as evidence. The fight unfolded in front of the Carl's Jr. next to the Powell Street BART station entrance.
Much of Shao's video was too violent to show.
"It made me disgusted to see it," Shao said. "But, also like I mentioned, it angered me."
Parts of the recording show him repeatedly punching and stomping the victim in the face. Someone can be seen in the video attempting to break it up. Shao said bystanders called police.
"On one hand I was surprised," Shao said. "On the other hand, I was really frustrated to hear this has been an escalating ongoing issue."
Last week, another video was taken of a man getting stomped on and assaulted on Mason Street, a few blocks away from the latest fight.
"The victim was being wrestled," Shao said. "He was being choked. He was gasping for air."
Shao said she usually sees officers around the area. "But on that day at that moment," Shao said. "Where were they? I didn't see a single one."
The victim suffered life-threatening injuries and was transported to a local hospital, where he was recovering.
Kelly is facing felony charges of attempted murder, robbery, mayhem, assault with a deadly weapon, resisting arrest, and multiple narcotics charges.
Video shows brutal attack near Powell BART station in San Francisco