In the video the boy is seen being slammed to the ground and then punched in the face as he lies facedown unconscious. He was also hit in the back of the head with a skateboard.
"I remember waking up in a pool of my blood and having seizures," said the victim, Thomas Schnider Jr.
The attack happened Monday outside a Stater Bros. grocery store in Norwalk.
Schinder's mother said this was a brutal attack by three other boys her son's age.
Schinder said he and his friend had been previously harassed by the same group.
Two juveniles, ages 14 and 16, have been arrested in the attack. They are in juvenile detention, facing felony assault charges.
"We don't know what started it," said Det. Mark Christiansen of the Los Angeles County Sheriff's Department. "And did he deserve it? No, absolutely not. In that sense, it's shocking."
Schinder is now recovering from a fractured skull, cheekbone and arm.