Watkin and Humberstone were at a house in Eastfield Grove, Peterborough, with another woman, Rachel Speechley, 26, and two other men on November 8 when a disagreement led to violence.
Watkin and Humberstone began kicking and punching one of the men and knocked him to the floor. They continued the attack until he was unconscious.
They carried him out to the pavement by his trouser belt and stamped on his face and neck before throwing a bag at him and walking away.
A nearby CCTV camera and camera phone footage from a passer-by captured the assault.
When officers arrived they called an ambulance before arresting the suspects.
The victim suffered severe swelling and bruising to his face, a swollen left eye, a cut to his left ear and extensive bruising to the left side of his neck.
Yesterday at Peterborough Crown Court, Watkin, of Mendip Grove, Peterborough, was jailed for four years, and Humberstone, of Eastern Avenue, Peterborough, was jailed for three years and eight months. Both had admitted causing grievous bodily harm (GBH) with intent.
Speechley, of Somerby Garth, Peterborough, pleaded guilty to affray and was handed 12 months in prison, suspended for 18 months, and ordered to complete an alcohol treatment programme.
Detective Constable Thomas Adams said: "This was an horrific and senseless attack, which left the victim with terrible injuries.
"I am glad justice has been done today and my thoughts are with the victim, who I hope will be able to make a full recovery, both mentally and physically, after this ordeal."