Broadcaster CNN aired the footage on Thursday captured by cameras in a Phantom Fireworks store in Matamoras, Pennsylvania, which is said to show Faisal Shahzad purchasing M-88 firecrackers.
M-88s were a component in the bomb placed in a black sport-utility vehicle and parked in the heart of New York. The bomb never detonated, and a street vendor alerted the police of the suspicious vehicle.
Shahzad, a 30-year-old naturalized US citizen from Pakistan, was arrested on Monday while trying to flee the country at John F Kennedy International Airport.
Shahzad faces charges that include attempting to carry out a terrorist attack.
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