Iconic funnyman Billy Crystal makes a welcome return to film comedy in the delightful “Standing Up, Falling Down,” which debuted at Tribeca. Things are not going according to plan for Scott (Ben Schwartz), a stand-up comedian who slinks back to Long Island after striking out on the Los Angeles comedy scene. Humiliated by having to move back in with his family, Scott is also haunted by what could have been with Becky (Eloise Mumford), the hometown girlfriend he abruptly left for the West Coast. Wracked with doubt and facing the prospect of a soul-crushing “real” job, Ben finds an unexpected connection with Marty (Crystal), a local dermatologist and charming barfly with a penchant for karaoke. Scott learns that Marty’s larger-than-life personality and alcoholism mask past disappointments of his own. As their unlikely friendship evolves, Marty and Scott both find the strength to start confronting their long-simmering regrets. The fine cast also includes Grace Gummer, Jill Hennessy, and Nate Corddry.