In 1980, the head usher at the Pasadena Civic Auditorium gives his crew a pep talk: he wants tonight’s “Betty Midler” show to go smoothly. He’s a little worried about risque language, Liberace recently gave him a scare. Then, boom, there she is, with her backup trio, “The Harlettes,” going from rock to ballad to medley, from “Big Noise From Winnetka” to “I Shall Be Released.” It’s a concentration of camp: she imitates Sophie Tucker, she’s mermaid Dolores Delago, and between every song, it’s non-stop movement and lots of raunchy patter.