Disney's research lab publishes a lot of fascinating work, but it's not always obvious what their end-goal is. In this case, though, we can safely say: Disney is building a Tigger.
They're calling it a single-legged hopping robot, but it's impossible that the company wouldn't try and develop it into a bouncy, trouncy, flouncy, pouncy Tigger-bot. Think Sphero's rolling BB-8 toy, but more likely to cause substantial damage to your home and pets.
The robot is built around a central voice coil actuator (yep, the same thing that moves in and out in speakers), and a pair of springs to give it extra bounce. A flat platform on the top of this houses the batteries, sensors, and controlling computer, and the whole thing is balanced by an algorithm that was trained in 3D simulations. The result is a robot that can hop about untethered for up to 19 jumps before falling over.
Of course, turning this prototype into a commercial product would take a lot of work. You'd want more than 19 hops on average, a costume that made it look like Tigger (which would need accounting for in the balancing algorithms), and maybe even a controller. For now, the most wonderful thing about single-legged hopping robots, is that this is the only one.