His documentary, When We Were Kings depicts the iconic heavyweight boxing match: The Rumble in the Jungle between Muhammad Ali and George Foreman.

Gast co-directed the 1977 documentary, The Grateful Dead Movie with guitarist Jerry Garcia.

The film captured the band's October 1974, five-night performance at the Winterland Ballroom in San Francisco.

A native of Jersey City, New Jersey, Gast graduated from Henry Snyder High School and studied dramatic arts at Columbia University,[1][2] and in that same period worked on the television series High Adventure with writer and broadcaster Lowell Thomas.

[1] The film details the boxing match known as "The Rumble in the Jungle" between Muhammad Ali and George Foreman.

Gast was hired to create a documentary about a three-day music festival that was happening in Kinshasa when the fight was occurring.

Gast won an award for the documentary and was eventually premiered at Radio City Music Hall.

Gast's 2010 project is a documentary entitled Smash His Camera, a film about paparazzo photographer Ron Galella.

Galella “is best known for his obsessive ten-year pursuit of Jacqueline Kennedy Onassis, which resulted in a lengthy court case weighing the rights of the press vs. the individual's fight to privacy.”[5] Gast directed his second documentary on a boxing legend, Manny, with Ryan Moore.