CAIRO — An amateur video that surfaced Sunday appears to show a crowd removing the motionless body of Ambassador J. Christopher Stevens from a window of the American mission in Benghazi, Libya, after it was attacked last week by Islamist militants, adding new details to reports that Mr. Stevens had died of smoke inhalation while locked in a safe room.

The video emerged as a new disagreement broke out between the recently named president of the Libyan Parliament and American officials over whether the attack was planned and whether Al Qaeda had a role.

Labeled the work of Fahd al-Bakkosh, the video centers on what appears to be the same tall, narrow window that witnesses have described as Mr. Stevens’s last exit. The witnesses said residents drawn to the scene had forced open the window and found Mr. Stevens behind a locked iron gate, pulled him out and taken him to the hospital. In the video, none say anything that shows ill will.

“I swear, he’s dead,” one Libyan says, peering in.

“Bring him out, man! Bring him out,” another says.