After Gulf oil spill, filmmaker returns to see what happened when the cameras had gone

Summary: More than four years ago, the Deepwater Horizon oil rig exploded, gushing oil into the Gulf Coast for almost three months before it was capped. Despite settlements and clean-up efforts, some communities have never fully recovered. Filmmaker Margaret Brown joins Hari Sreenivasan to discuss her documentary, "The Great Invisible," which examines the fallout.