In the 90-second clip, a group of people appear to come to the blows on the rugby pitch at night as those in the scrum swear loudly.
The spectators repeatedly shout “call the police” and in the foreground a woman is completely still on the ground.
The bride is then seen lying in her wedding dress on the grass while two men – one in a suit – are seen struggling on the floor before a male voice shouts “get down”.
Penlan Rugby Club posted a statement on Facebook saying they were aware of a fight after a wedding party at their clubhouse.
The statement added: “It was a private function and no one affiliated with the club was involved.
“We hope everyone is safe, the club staff called the police and had people kicked out and the injured drew attention. This behavior can cause life changing injuries. We are fortunate to have such great members who helped with the cleanup.
“I hope everyone who participated is safe because the behavior and the fighting was completely unacceptable and dangerous. “
South Wales Police have confirmed they are investigating the incident.
A force spokesperson said: “We were called to reports of a disturbance at the playing fields near the Penlan Rugby Club at 11:35 pm on Friday September 4th.
“The officers were present and inquiries are ongoing. Anyone with information should contact 101 citing event 2000324041. ”