Jennifer Lopez was in fine form at yesterday’s taping of her dance performance for the finale of Fox’s “So You Think You Can Dance?” “She brought Marc Anthony and the kids along to watch, and she kept going over to the microphone to talk to them between takes,” says an observer. “The audience was eating it up. It was very cute.” Lopez, who sang her new single, “Louboutins,” showed no sign of letdown after her minor tumble at the American Music Awards. “She nailed it,” says our spy. “Even the background dancers were impressed.”