Bringing a portrait of private artist Vivian Maier to the big screen

In 2007, a monumental cache of photographic negatives were sold at auction. The man who bought them, John Maloof, soon discovered stunning images of Chicago street scenes from the mid-20th century. Who was the unknown artist behind the photographs? Jeffrey Brown talks to co-directors Maloof and Charlie Siskel about their Oscar-nominated documentary, “Finding Vivian Maier.”