In a move that will allow movie studios to inject racy jokes into the trailers they use to promote their more adult-oriented films, the nation's largest theater chain has decided to permit restricted, "red band" trailers in its multiplexes. The move by Regal Entertainment Group, which operates 6,388 screens in 39 states and the District of Columbia, likely will lead to similar decisions at a number of the nation's other major chains. As last week's ShoWest convention of movie theater owners in Las Vegas drew to a close, the Knoxville, Tenn.-based circuit began notifying the studios of its decision. The...