American siblings trapped in China make plea for help

"A pair of American siblings trapped in China are making a public plea for help. In a video you'll see only on ""CBS This Morning,"" Cynthia Liu describes the terrifying ordeal for her and her brother Victor. The two traveled to the country last year but have not been allowed to return home to the U.S. because of a so-called ""exit ban.""

Margaret Brennan reports. "