Alarm kid

A toddler in a striped shirt and overalls stands in a modern room, reaching out and then pointing at a glass door, reacting with surprise and a wide-open mouth as they realize the glass is solid. The scene then cuts to a black and white image of a large, multi-speaker horn array on a rooftop, followed by a black and white scene of people in period clothing gathered around a hole in the ground, appearing to assist someone.