Martha Hardison of Popular Science said this about video of a bridge being demolished in Texas this weekend…
I love how the first two passes of the video — real-time and semi-slo-mo — it’s difficult to see exactly how the demo goes. But the third time, look closely under the bridge. You can totally see the detonator cords burning up ahead of the ignition of the shaped charges that brought the trusses down. The video also clearly demonstrates the difference between the speed of light in air and the speed of sound in air — the flashes from the charges are long gone by the time the sound waves make it to the filming location.