Piers Gibbon once hosted a National Geographic special called "Eating With Cannibals'' that featured the British explorer in Papua New Guinea with a tribe that still practices cannibalism. Perhaps after that experience it makes sense that Gibbon presents "The Witch Doctor Will See You Now.'' The four hourlong episodes document some of the world's most ancient and extreme medical practices, from the snake-soup healer in Hong Kong to the chicken-massaging witch doctors in the African country of Cameroon. Gibbon is joined by volunteer patients who are seeking cures to their own ailments, something Western medicine has failed to achieve.