Showtime's "In the 20th Century" is a millennium-related strand of feature-length documentaries in which famous directors take on major subjects of their choosing. In the third of the six films, "Yesterday's Tomorrows," filmmaker Barry Levinson delves into what we, as Americans, thought the future would be as we traveled through the 20th century. Houses and cars of the future, the promise of technology, and the other hopes and dreams of the early part of the century gave way to the fears and anxieties brought about by the atomic age and the Hollywood disaster films that followed. Soon we wondered if we could control technology, or if it would control us. This film is by turns light-hearted and thoughtful, and rare historical and archival film, produced by government and industry, alternates with on-screen interviews with people as diverse as consumer advocate Ralph Nader, cartoonist Matt Groening, futurist Alvin Toffler, comedienne Phyllis Diller, and actor Martin Mull.