Taliban footage of U.S. soldier real or not?

An allegedly authentic video of a U.S. Soldier captured by the Talibans The soldier is purportedly a captive since around five months ago.
Pfc. Bowe Bergdahl is currently and officially the "only known American serviceman in captivity". Bergdahl is a U.S. airborne infantryman, and was apparently captured and abducted by the Taliban on June 30th in the Province of Paktika, in Afghanistan.
The American Navy's Rear Admiral, Gregory Smith gave a statement saying;
"This is a horrible act which exploits a young soldier, who was clearly compelled to read a prepared statement."