From In70mm.com about the Showscan Dynamic Motion Simulator:

Intamin Corporation Inc. Est. (“Intamin”), a Liechtenstein corporation that is a manufacturer of amusement park rides, has developed hydraulically actuated theater seats that can be synchronized with a film image projected onto a screen in front of the seats. By synchronizing the motion of hydraulic seats with the projection of an action Showscan film, the Company and Intamin have been able to simulate the experience and motion of a ride, such as a roller coaster, a racecar or a submarine. The theaters in which such mechanized seats and Showscan equipment are installed are called Dynamic Motion Theaters. The Company and Intamin anticipate that Dynamic Motion Theaters will be established to simulate a series of approximately two to four minute action rides and intend to market the theater to amusement centers, tourist attractions and other locations frequented by large numbers of people, possibly including shopping centers.