The below video has the added bonus of a new bluesy theme song, with a beat seemingly written to match BigDog's jaunty gait.

BigDog uses a system of hyper-responsive hydraulic joints, sensors, accelerometers and gyroscopes to keep it on its four legs. Boston Dynamics says the creature can run at 6.4 kph, climb slopes up to 35 degrees, walk across a wide range of terrain, and carry 154 kilos. It's designed to go wherever humans would go, carrying their load without complaint or the urge to sniff the ground every couple of seconds. It's funded by DARPA, naturally.

In pup mode, it performs a doglike "let's-play" stretch; later in its life, it gets down to business, leaping like a greyhound and tromping through the snow like an AT-AT walker. Turn up the sound and check it out.