Juneteenth: The story behind the 155-year-old holiday that commemorates the end of slavery

On June 19, 1865, 155 years ago Friday, the last group of slaves in the United States were freed. Their freedom was bittersweet -- it came two and a half years after the Emancipation Proclamation was issued in 1863. CBS News special correspondent James Brown shares the story of the day that became known as Juneteenth.