Q. Why does the loudness of a sound wave decrease as the wave travels away from its source?
A. The energy in the sound's vibration dies down, until it is no longer audible.
... have to do with this man in the video? And what does it have anything to do with Torah?
"Sound waves dissipate over time and distance, but never fully disappear. But the energy still remains, even at some infinitesimally small level. What that means is that the sound of Hashem giving the Ten Commandments all those years ago at Har Sinai IS STILL IN THE WORLD TODAY. We just don't have the sensitivity to hear it."
Pretty amazing, eh?