“It has become a custom every year for me to humiliate myself,” Elton said – at which point he launched into a version of “Diamonds Are a Girl’s Best Friend” while hunky actor Channing Tatum danced around him in a particularly eager bump-and-grind. Now that’s a sport. The choice of “Diamonds” (from the film “Gentlemen Prefer Blondes”) highlighted the night’s theme: “Songs of the Silver Screen.” Not that the participants always took the most literal interpretation of the motif. Many chose rock and pop hits that appeared in movies only after they were already well known, like Roy Orbison’s “Pretty Woman” or The Band’s “The Weight.” Other songs had a firmer connection to Broadway than movies, like “Old Man River” (from “Show Boat”) or “Shall We Dance” (from “The King & I”). But, hey, let’s not get too literal about this — especially given the unpretentious tone of the whole event. The light-hearted night featured not just rainforest regulars (Sting, Elton, and James Taylor), but also Rosanne Cash, opera star Bryn Terfel, Meryl Streep (yes, singing) and — just to show that the organizers had some awareness of what century they’re in — Bruno Mars, Jennifer Hudson and surprise guest Esperanza Spalding. Wisely, Streep chose to appear in character pieces, allowing her to act her way through. She sang Judy Garland/Dorothy Gale’s part in “If I Only Had a Heart,” which also featured Sting as the Tin Man, Taylor as the Scarecrow and Elton as the Cowardly Lion. Streep also mixed it up with Sting on “Let’s Call the Whole Thing Off,” whose subtext ranked on her fetish for accents.