Resurrection Biology: How to Bring Animals Back From Extinction

We've all seen the movies and heard the hype: But is it really possible to bring back animals that have gone extinct? If so, how? And how soon? And can I have a mammoth to ride around in my backyard? Hank explains the latest research into resurrection biology, and ponders questions that include not only "Can we?" and "How do we?" but also: "Should we?"