BAGHDAD — The women of Saeed Chmagh’s family wept, but the men did not as they watched a video of him being shot to death by a gunner on an American Apache attack helicopter.

“I saw the truth,” Samir Chmagh, 19, son of the dead man, said Tuesday in his family’s living room in Baghdad. “They saw clearly that they were journalists and that they were holding cameras. It was painful when we saw this movie.”

It was a fog-of-war moment in July 2007 on the streets of Baghdad in which American troops gunned down men they identified as insurgents. The attack left 12 people dead, including Namir Noor-Eldeen, a 22-year-old Reuters photographer, and Mr. Chmagh, 40, a driver and assistant for the news agency.

A video from the cockpit of an Apache helicopter was released on Monday by WikiLeaks.org, an online organization that said it had received the video from a whistle-blower in the military. The video has become an Internet sensation, with defenders saying the soldiers believed they were under threat and critics denouncing what they said were callous and bloodthirsty comments by the soldiers as they killed about a dozen people.