From the moment Thomas Edison shocked the public with May Irwin's unabashed kiss, the movie industry has become a battlefield for audiences who can't get enough of a good thing - and critics who believe some things are better left behind closed doors. SEX, CENSORSHIP AND THE SILVER SCREEN, a six-part documentary written and directed by Frank Martin traces the evolution of sexuality in America film, from the silent-film vamp Theda Bara to Elizabeth Taylor to the temptresses of ''Showgirls.'' Harrison Ford, Melanie Griffith, Marisa Tomei and Daryl Hannah recreate the voices of Hollywood legends to chronicle the continuing clash between screen sexuality and censorship. Raquel Welch is the host.