A Winthrop man is facing charges for allegedly stashing a device in a teenager’s bedroom to secretly videotape the girl, Suffolk District Attorney Daniel F. Conley’s office said. On Wednesday, Brandon White, 29, allegedly hid an iPad Mini in the bedroom of a 14-year-old family friend, capturing video of the girl in a state of nudity, prosecutors said. The girl discovered the device and family members reported the incident to police, prosecutors said. White is charged with photographing an unsuspecting person in the nude and exhibiting a child in the state of nudity; a plea of not guilty was entered for him at his arraignment Friday in East Boston District Court.Lauren Dezenski can be reached at email@example.com. Follow her on Twitter @Lauren_Dez.