During the Comic-Con, they showed a pretty long video of some animation that they did for Book Two: Spirits. It features Bolin pro-bending without Korra and Mako, and, well, the new Fire Ferrets are horrible (besides Bolin). Mako is now some kind of cop, and it shows him hunting some gang down. Asami took control of Future Industries, but because of it's previous Equalist ties, nobody wants to work with them, making them almost bankrupt. Korra isn't taking her new Avatar powers seriously. Jinora, Ikki, Meelo, and Korra all race on air scooters, but suddenly, Korra goes into the Avatar state and leaves the three in the dust. Tenzin then scolds her saying that she doesn't appreciate her new-found powers and stuff.
Alright, enough talking, here's the video!