How shows like 'Mad Men,' 'Vikings' deal with less progressive pasts

Creators of historical dramas like 'Copper' and 'Downton Abbey' know they have to walk a fine line when it comes to culturally sensitive (or not) portrayals.When Ato Essandoh was offered the role of an African American doctor in Civil War-era New York City for BBC America's "Copper," he almost did a double-take. "My first thing was I had to look it up," he says. "Lots of people didn't really think there could have been an African American doctor in existence back then."