In March and April of 1966, Markopoulos created this filmic portrait of writers and artists from his New York circle, including Parker Tyler, W. H. Auden, Jasper Johns, Susan Sontag, Storm De Hirsch, Jonas Mekas, Allen Ginsberg, and George and Mike Kuchar, most observed in their homes or studios. Filmed in vibrant color, Galaxie pulses with life. It is a masterpiece of in-camera composition and editing, and stands as a vibrant response to Andy Warhol's contemporary Screen Tests. Preserved by the Academy Film Archive in 2001.

In 1963 Boultenhouse wrote, produced, and directed Dionysius,which he described as a “free treatment of Euripides' The Bacchae.”It starred the dancers Louis Falco, Anna Duncan, and Nicolas Magallanes as Dionysius, Agave, and Pentheus respectively, and the experimental filmmakers Charles Levine, Willard Maas, Gregory Markopoulos, Marie Menken, Lloyd Williams and William Wood as the Chorus of Cameras. The film's score was by Teiji Ito.

Because of the film's choices of text and illustration were made so well – and because the natural anatomy of memory is so like that of cinema montage– the movie's effectiveness is very great, and it stands as a worthy initial exploration of the medium in which Mr. Boultenhouse has wrought so well. –Wallce Thurston, Kulchur #16