The video, obtained by The Associated Press, includes a message from the Pakistani Taliban claiming they fired a missile from a distance of 3 kilometers (1.9 miles) to down the helicopter Friday.
"The missile hit the tail rotor," a written message in Urdu says at the video's start.
The crash killed the ambassadors to Pakistan from the Philippines and Norway and the wives of the ambassadors from Malaysia and Indonesia, as well as three Pakistani crew members. Twelve passengers, many of them diplomats, were injured.
Military officials could not be immediately reached Sunday to discuss the video. Previously, Pakistan said a technical failure caused the crash and dismissed an earlier Taliban claim they shot down the helicopter as opportunistic.
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However, the surface-to-air missile shown in the video appeared real. In the video, a masked militant discusses the missile's parts, while another portion shows what appears to be a hand-drawn picture discussing how a missile can strike a helicopter's tail rotor.
The video was released late Saturday via militant websites and corresponded to other messages distributed by the Pakistani Taliban, though the AP could not independently verify it. Militants in Afghanistan and Pakistan do have access to surface-to-air missiles.
Pakistani security forces have been battling militants in the country's northwestern tribal regions bordering Afghanistan for the past several years, though the fighting took on a new urgency after a Taliban attack in December on a military school killed 150 people, many of them children.
The helicopter's crash site Friday in Naltar is several hundred kilometers (miles) from the North Waziristan tribal area, where fighting recently has been focused.
Aircraft and helicopter crashes have happened previously in Pakistan, a nation of 180 million people.
