The BBC said the images seemed to contradict US accounts of what happened in the town of Ishaqi, north of Baghdad, in March.
The US army initially said four people had died during a raid to find an al-Qaeda supporter in which a building collapsed.
However, Iraqi police said 11 civilians, including five children and four women, were shot and killed by US troops who then blew up the building.
The video footage shows a row of bodies, many displaying what seem to be gunshot wounds.
The video was obtained from a Sunni group opposed to US-led forces, the BBC said.
The US army said it was investigating the incident, the BBC added.
The news comes as a US military investigation into the killings of 24 Iraqi civilians by marines in the town of Haditha in November is expected to conclude that troops lied to their superiors, who did not fully investigate the allegations.
The US initially said the dead, including women and children, had been killed by a roadside bomb.
However, Iraqi witnesses and a US media report said that they were shot and killed by US marines.
A US defence official has said about 12 marines would face charges, including for murder, over the incident.
There are two US investigations into the killings, along with one announced by Iraqi authorities.
On Thursday, US military prosecutors also planned to file murder, kidnapping and conspiracy charges against seven marines and a navy corpsman for shooting and killing an Iraqi civilian in April, one of the men's defence lawyers said.
The US army announced earlier this week that US-led troops in Iraq would have ethical training, following concerns about Haditha and other incidents.