U.S. authorities are interrogating Pakistani-born Faisal Shahzad for his alleged role in a plot to detonate a car bomb in Times Square in May.
He is charged with acts of terrorism and an attempt to use a weapon of mass destruction.
In a recently uncovered video, released by Flashpoint Global Partners, Shahzad is allegedly shown alongside Pakistani Taliban leader Hakimullah Mehsud saying, "We are planning an attack," the online intelligence forum The Long War Journal reported Friday.
Shahzad reportedly told his interrogators that he received explosives training by militants in Pakistan. The Pakistani Taliban claimed responsibility for the attack, though New York and Pakistani authorities questioned the claim.
FBI authorities raided several sites in greater Boston, New York and New Jersey in connection to the attempted Times Square bombing May 1.
Bruce Riedel, an expert on terrorist groups at the Brookings Institution, said al-Qaida's ideology of attacking the United States, "the ultimate enemy," is spreading beyond the central terrorist cabal to other groups like the Pakistani Taliban.
In a May interview with the Council on Foreign Relations, he noted that the Pakistani Taliban claiming responsibility for the Times Square plot, a first for the group, was a dangerous precedent.
Shahzad pleaded guilty to the charges in June.