The tanks performed twice at the Engineering Technologies 2012 exhibit for potential government buyers from developing countries and military attaches in Moscow. Over the weekend, the show opened for the public and was caught in this amateur video posted on YouTube (above). Later this week, Russian Technologies, the parent company of Rosoboronexport, plans to release a professional video that will be used to promote the weapons system, a spokeswoman said. He choreographed the machines, which range in weight from about 42 to 47 tons based on their configuration, to excerpts from "Carmen," the opera by Georges Bizet. They pair up and separate, lower their guns like lances and charge at one another. The tanks, and at times a self-propelled artillery piece, are maneuvering on a square 30 yards by 30 yards at an airfield used for military exhibits in Zhukov. The self-propelled artillery is an MSTA-C 152-millimeter howitzer. Mr. Melanin emphasized the challenge that the tight space posed to the tank crews. The drivers could not hear the music; instead, Mr. Melanin shouted orders over a radio. This performance, also choreographed by Mr. Melanin, opened with Igor Stravinsky's "Rite of Spring" and Pyotr Tchaikovsky's "1812 Overture." The Tchaikovsky composition's cannon shot was performed by a tank firing a blank through its 125-millimeter main gun. The ballet moves, in fact, illustrate a feature of Russian tanks often highlighted in public demonstrations: the ability of the computerized turret hydraulics to stabilize the main cannon. This capability fixes the weapon at an azimuth relative to a distant target even as the tank bobs or turns underneath; the Russians have claimed particular skill in designing these systems.