Britain said all 10 personnel on the flight were missing and presumed dead.
The authenticity of the video could not be confirmed. It showed a finger pressing a button on a white box with wires, and then images of two missiles or rockets flying up into the air. The video did not show any impact with a plane. Instead, it cut to footage of people walking through a plane’s wreckage burning on the ground.
It was not immediately possible to determine if the wreckage was that of the British C-130 Hercules that crashed on Sunday, about 25 miles north of Baghdad.
In London, officials at the Foreign Office said they were aware of the reported video, but offered no further comment.
A spokesman for al-Jazeera said the television station received the video from a group that called itself “the Green Brigade,” part of “the 1920 Revolution Brigade”, a military wing of the National Islamic Resistance in Iraq.
Earlier, a different group, Ansar al-Islam, claimed in a web statement that its fighters shot down the flight.
A spokesman for Britain’s Ministry of Defence said earlier he could not confirm Ansar’s claim or that the plane was downed by insurgent fire. He said experts were at the site trying to determine the crash’s cause.
British Defence Secretary Geoff Hoon said nine British air force personnel and one soldier were missing and believed killed in the crash, which would make it the deadliest single incident for British forces in Iraq since the war began in March 2003.
An insurgent group called “The 1920 Revolution Brigade of the National Islamic Resistance in Iraq” first emerged in Iraq’s Sunni Triangle in July 2003. But the Green Brigade of that group has not been heard of before.