How do you celebrate losing 30 lbs. on Weight Watchers? If you’re Oprah Winfrey, and you own a stake in the company, you make a surprise appearance at a group meeting! The 62-year-old did just that yesterday, before debuting her new OWN series, “Greenleaf” at the Tribeca Film festival today. “Extra’s” AJ Calloway caught up with Oprah to talk about everything from Michael Strahan leaving “Live with Kelly and Michael,” to weight loss, to “Greenleaf.”