Whenever documentary filmmakers at Discovery Channel and the BBC unite for a project, stellar television seems to follow. "Planet Earth: Africa" stems from this collaboration, as did the breakthrough natural history series "Life" in 2009. David Attenborough narrated that one, and he's back to take viewers on a journey through the vast and diverse continent of Africa. Four years in the making, during which more than 2,000 hours of video were shot, the program consists of six hour-long episodes that feature an array of never-before-filmed species, animal behaviors and previously unknown places. Cameras uncover the extreme dangers of the Kalahari, the dense forests and snow-capped peaks of the Savannah, the dynamic Congo rainforest, the ever-changing climate of the Cape and the massive and parched Sahara.