Moner Mohammad Abu Salha, alias Abu Hurayra al-Amriki, was believed to be the first American national to carry out such an attack in Syria's more than three-year-old war.
"I want to rest in the afterlife, not in this world... My heart is not at peace here. Hopefully it will be in heaven," Abu Hurayra says in broken Arabic in the 17-minute video posted on YouTube by Al-Nusra Front.
The footage, released via Al-Nusra's official channel Al-Manara Al-Baydaa, also shows Abu Hurayra saying: "I came to Syria without money to buy a rifle or a pouch.
"God gave me a rifle and a pouch and everything, and... (then) he gave me even more."
The American jihadist carried out a May 25 truck bomb attack on an army base in Jabal al-Arbaeen area of northwest Syria's Idlib province, AFP reported.
The State Department confirmed that the US citizen, who newspapers said was from Florida and travelled to Syria in 2013, had carried out a suicide attack.
Estimates of the number of foreign fighters who have flooded into Syria in the past three years range from between 9,000 to 11,000.