Kerry Jackson, who recorded the video, can be heard in the video screaming, along with neighbours and family members, for the child to jump.
Jackson said the boy, who initially resisted calls to jump, landed in the arms of his cousin.
"Every time you watch it, there he go he jumped, he jumped, he finally jumped," Jackson told local television station WBRC. "It's just that feeling it gives you just to relive that moment and say you saved someone's life. It's just a really good feeling,"
Six people, including two children, were injured in the fire. One child remains in critical condition at a local intensive-care unit, according to WBRC.