‘Piano Man’ popcorn play

HE’S going from “Piano Man” to popcorn man. Page Six has exclusively learned that rocker Billy Joel has donated funds to rebuild the Hamptons’ beloved Sag Harbor Cinema after it was burned in a fire, and the popcorn stand will be named after him out of gratitude. Meanwhile, we’re told that Harvey Weinstein and Martin Scorsese have also chipped in to help the Sag Harbor Partnership raise the $8 million it needs to complete the project. Headed by artist April Gornik — wife of painter Eric Fischl — the partnership is buying the damaged theater from its owner of 38 years with the aim of raising funds privately from donors to launch a Sag Harbor Cinema Arts Center with year-round “education, outreach and programming.” Plans include the preservation of the large, historic “curved scope” screen, plus two others, and the addition of a “locally owned and sourced cafe.” The group says it still needs to pull together $6 million in donations by July 1 to “protect current donations.” A “Big Tent Party” is scheduled for July 16. It seems that the guest list, at least, will be starry.