The presenter calculates the time it takes light reflected off the Moon to reach our eyes. As the Moon is 400,000 km from Earth and the speed of light is 300,000 km/s, the time taken is about 1.3 seconds.
This clip could be used to introduce the idea of the Solar System and relevant distances of objects within it. This can lead into calculations of distance of stars from Earth. It could then be extended to consider light years and why this unit of measurement is used.