Playwright Jonathan Tolins talks about his play “Buyer & Cellar,” along with Michael Urie, who stars in it. It’s about a struggling actor in L.A., who takes a job working in the Malibu basement of a megastar. One day, the Lady Herself comes downstairs. It feels like real bonding in the basement, but will their relationship ever make it upstairs? It’s playing at the Barrow Street Theater and has been extended through mid-October.