Anthony Tommasini has already noted in The New York Times that this apparatus — which often resembles a kinetic sculpture — may be at its best when quietly stationary, functioning foremost as a video screen, and he may be right. The structural flexibility of the machine should not be overlooked. Whirling and flipping, rising and falling, in unison or separately, its 24 big planks approximate the sometimes steep, sometimes gentle banks of the Rhine and Siegfried’s raft as he rides down it; the mountain keeps of Wotan and Fricka and the walls and drawbridge of Valhalla; the Nibelung underworld and other caves; an assortment of dense forests; a castle on the Rhine; and a house deep in the woods. But they only approximate; it is video that clinches these illusions, defining the machine’s abstract forms with colorful, textured, often hyper-realistic skins.

The Lepage “Ring” is really an orgy of video, carefully sequenced and impeccably presented, relayed by 10 high-definition projectors and aided by sparing use of motion sensors and even voice-activated imagery (the bubbles rising behind the Rhinemaidens as they dangle, singing, in front of the machine’s vertical face projected with watery blue waves). There is even a live-action projection or two, as when Siegfried, gazing down into a quiet mountain stream, is greeted by a reflection that matches his every expression and gesture.

Video adds scintillating expanses of pebbles to the banks of the Rhine that scatter and cascade whenever the dallying Rhinemaidens touch them, or Alberich, desperate for love, clambers up or is pushed back down. It creates swirling clouds and jagged spikes of lightning in the realm of the gods; rock textures in various realms; torrential, flowing, trickling or gently pooling water; several varieties of tree trunks; and quantities of fire. Flames dance around the feet of Loge, the fire god and Wotan’s right-hand man. Molten lava flows among the rocks when Wotan commands Brünnhilde not to aid Siegmund in his battle with Hunding.

And of course flames, projected onto the jutting planks of the machine, form the ring of fire with which Wotan surrounds Brünnhilde when, as her punishment for disobeying him and trying to save Siegmund, he strips her of her godly powers and puts her to sleep. This fire-ringed mountaintop figures in three of the four operas in the “Ring” cycle and becomes a bit tedious; its animated cracklings start to suggest an unusually large version of fake logs while also dwarfing the singers.

What I saw at the Met was not so much video art as a very advanced, dazzlingly mutable version of stage-set painting, which is perhaps even better, or at least more useful. Video’s light-filled immateriality and the ease of scene-changing seem especially suited to the way Wagner’s narrative roams through time and space — to spheres both natural and imagined — with little regard for logistics. At times the mutations themselves are riveting to watch. At the beginning of “Die Walküre,” for example, the gray flat-sided planks rise to the vertical position, and as they go, video projections turn them into round, soaring tree trunks seen through drifting snow, then they flip inward at the bottom to become the sloping ceiling of Hunding’s forest dwelling and in a twinkling are transformed into milled beams.