Jerry Springer, The Opera is a big hit in London, and Ben Brantley loves it. “Who could possibly forget that exultant song of self-celebration that begins, “This is my Jerry Springer moment . . .”? That number, performed by a grown woman in baby clothes on a swing, comes from “Jerry Springer: The Opera,” the four-alarm fire of a show at the National Theater, and I find myself singing it while doing household chores, the way my mother used to with melodies from “Oklahoma!” and “My Fair Lady.” The scary part is that though it’s a song about parading your exotic sexual tastes on national television, I don’t think, “What a camp,” when I remember it; instead, I feel kind of starry-eyed.”