This is a video of a dinosaur on the loose in the LA Museum of Natural History. The overall effect is pretty compelling. The movements are very well controlled.

Not suprisingly, it's not a 'real' robot. There's a pupeteer inside controlling the action, with a lot of motorized assistance. What is suprising is that the on you saw above is the small version. Check out this video showing their construction, and a few of the larger models.