The singer -- who had just performed "I Dreamed a Dream" from "Les Miserables" and the sentimental love song "Cry Me a River" on the morning TV talk show before a live audience at New York's Rockefeller Center -- appeared to cry after receiving a hand-stitched quilt made by hundreds of fans from around the world, the video indicated.
She went to a cafe overlooking Rockefeller Center's famous ice-skating rink and cried, putting her head in her hands, the video showed.
Moments later, apparently realizing her fans were watching, she composed herself and performed a little dance, Britain's Daily Telegraph reported.
"She was just overjoyed and extremely touched with the reception she has had from everyone in America," a spokeswoman for the star said.
A source told The Daily Mirror the demands of Boyle's U.S. tour "would put anyone under enormous pressure."
"Everyone around her is acutely aware how susceptible she is to becoming emotional when under stress," the source said.
Boyle, 48, came to global public attention in April as a contestant on "Britain's Got Talent." Her first album, "I Dreamed a Dream," released Monday, has sold an estimated 700,000 copies so far, making it the biggest and fastest-selling release this year, after being the most pre-ordered album worldwide of all time.
A one-hour documentary, "I Dreamed a Dream: The Susan Boyle Story," produced by British TV personality and artists and repertoire executive Simon Cowell, will air on the TV Guide Network Dec. 13.