Continued conversation about how a registered sex offender is accused of secretly recording children at Boston’s Frog Pond and is facing dozens of new charges after police allegedly found videos of children changing clothes and using the playground. Prosecutors say the 60-year-old man used camera-equipped sunglasses and his cellphone to record children, and investigators found more than 40 videos on his devices. The disturbing case raises questions about how to protect children from predators in busy public places.