In the ADR listing of the end credits (at around 1h 23 mins), Ron Ruzika is listed as "Minus' voice" and Paula Halden is listed as "Edna's voice" (the secretary of the editor Larry at around 15 mins).
The listing for the motion picture copyright of Earth Minus Zero at copyright.gov includes "1/2 inch videocassette" as the Description, "1997" as the Date of Creation, "1997-10-15" as the Date of Publication, "1998-03-19" as the Date of Registration, and "PA0000888167" as the Registration Number. This would mean Earth Minus Zero was released directly to video on or after October 15, 1997.