Obama met former President Carter's grandson James Carter and his cousin, Georgia state Sen. Jason Carter, D-Decatur, last week at a post-State of the Union stop in Atlanta, CNN reported.
"After [Jason] got his picture taken, he told Obama that I was the one that had found the 47 percent tape," James Carter told CNN Thursday.
"Then Obama said, 'Hey, great, get over here.' And then he kind of half-embraced me, I want to say, put his arm around me, and we shook hands. He thanked me for my support, several times," he said.
In the secretly recorded video, leaked in September, Romney is heard saying: "There are 47 percent of people who are with him, who are dependent on government, who believe that they are victims, who believe the government has to care for them, who believe that they are entitled to healthcare, to food, to housing, you-name-it."
The video, recorded May 17 during a fundraiser in Florida, has been cited as a main reason Romney lost the election.
James Carter, an opposition researcher, said he found the video online and encouraged the person responsible for the tape to submit it to the left-leaning magazine Mother Jones.
"I obviously hoped that everything that I found would make a difference," he said. "It ended up being way beyond my wildest dreams."
Former President Jimmy Carter praised his grandson's work, telling CNN that he thought the video was a "pivotal moment" in the election.
"It was something [Romney] could not deny and it stuck with him for the rest of the election and I think it was a major factor, if not the major factor," he said.