One digital motion image after another, feels like installation art. Lot of scrolling or rotating wood textures. Other recurring things: a woman’s face, a man’s hairy body, a laser light show.
Leviathan over Arizona:

Preening seagull in flames before a MST3K planet floating over a mirrored river and floating heads staring back at us: it all feels vaguely satanic

Soundtrack by George Lockwood, that’s half the movie. I was already appreciating the sound effects, then after twenty minutes someone says the movie title out of the blue, sparking a series of dialogue clips from some noirish film(s). The credits list a ton of audio sources (the Prelinger archives of course, and some MST movies to match the spinning planet).
Sicinski
Jordan Cronk in Cinema Scope:
The Chocolate Mountains stretch in a southeast direction across the Colorado Desert … this 60-mile region, almost totally closed off to the public, is home to the Chocolate Mountain Aerial Gunnery Range … utilized by the US Navy and Marines to test aerial bombing and weapons technology. So it goes that Where the Chocolate Mountains, O’Neill’s first feature in over a decade, is not a film about its eponymous locale, per se, but a film about the idea of the Chocolate Mountains; most viewers are likely unaware that these particular mountains even exist. It therefore matters little that at no point in O’Neill’s film do the Chocolate Mountains actually appear.

–
Horizontal Boundaries (1997)
Each segment takes three or four strips of natural scenes or human activity and overlays them as they cut and move and slide over each other in a v-hold loop. After a few of these he breaks the pattern, an animation cross fading into an opening curtain, using a cloudy sky as image matte, stutter-loops from stock films on the soundtrack. Then a blaring siren loop and fast white pulses between a carousel of helicopter shots. Footage will loop around horizontally or vertically, the sense of time all manipulated and broken. Voices heard on the soundtrack were mostly from Dragnet.


