What are grief bots and how do they work

There's an emerging industry that uses artificial intelligence to create simulations of people who've died. These post mortem avatars are also called griefbots.

Some critics, including Tomasz Hollanek, a researcher at the University of Cambridge, say this practice raises a number of ethical issues. He walks us through the mechanics of how this technology works, and how it may or may not be used responsibly.