France's slave trade: Nantes residents come to terms with their past

May 10th marks France's official recognition of slavery as a "crime against humanity". It's a chance to look back at this dark era and its lasting effects on French society. Between the 17th and 19th century, half a million Africans were shipped across the world from the western port of Nantes. Our reporters take us to Nantes to meet some of the descendants of France's slaves - and slave traders.