Once upon a time, if you wanted to know if a movie was worth seeing, you didn't check out Rotten Tomatoes or IMDB. You asked whether Siskel & Ebert had given it "two thumbs up." On a cold Saturday afternoon in 1975, two men (who had known each other for eight years before they'd ever exchanged a word) met for lunch in a Chicago pub. Gene Siskel was the film critic for the Chicago Tribune. Roger Ebert had recently...