A 50-year-old nanny has been charged with child endangerment after she was caught on a nursery Web cam hitting and shaking the infant she was supposed to be caring for, cops said yesterday. Fook Moy of Elmhurst, Queens, was arrested after the 6-month-old's horrified mother watched Moy banging the child up and down on the floor, then placing a pillow over his head while smacking the pillow and yelling, "Stop crying! Stop crying!" cops said. The parents, who live in Roslyn Harbor, L.I., told cops they hired Moy on Jan. 2 to cover while their regular nanny went on...