The video was taken at the stadium during or after the game between the Jets and the New England Patriots.
In the video, a man wearing a No. 80 Jets jersey is seen punching the woman. The woman is wearing what appears to be a red and white Patriots shirt.
State police spokesman Sgt. Adam Grossman says the video, which was posted by the website Deadspin, is being reviewed. He says no arrests have been made.
The Jets say in a statement that "the parties involved were detained and this matter is now in the hands of the New Jersey State Police."
The mother of one of the men in the fight says the 38-year-old is not to blame -- even though he's seen on video punching a woman.
"She was the aggressor. She just came out of nowhere and started punching my son," said Colleen Paschke, who was there when the brawl broke out.
She says five Patriots fans, including two women, started fighting with her friends, when her son Kurt jumped in to break it up.
"He went over to pull them off the guy and girl and that's when they grabbed my son and started punching him. One guy was holding him while the other guy punched him," Paschke said.
What she describes wasn't captured on video, but in the clip that's gone viral, you can see Kurt in the chaos when he suddenly gets pulled back. A blonde woman lunges at him, and he throws a punch.
"She punched my son three times to the head, cut his eyebrow. My son just turned around to defend himself, like, enough, you know? Like, he was getting tired of being punched," Paschke said.
Kurt Paschke was interviewed by police after the fight, as were the other people involved. Initially, he was told no charges would be filed, but now New Jersey State Police are only saying it's an ongoing investigation.
Kurt Paschke has a criminal history. In 2011, he was caught serving alcohol to minors while bartending. In the 1990s, he served two-and-a-half years in prison for fatally stabbing a teenager. But his mother says he was wrongly convicted.
"It happened many years ago when he was only 17. He was set up by a white supremacy group and unfortunately he ended up taking the blame for the stabbing of another youth," Colleen Paschke said.