"Consider the three largest moons of Jupyter. Europa takes exactly twice as long as IO to orbit Jupyter, and Ganymede takes exactly twice as long as that. How can that be? This is an example of synchronization, but what's the mechanism? That's what this video is about: it's an explanation of something called orbital resonance."
It's an equilibrium effect that occurs with at least one body is in an elliptical orbit. In this case it causes all the rubble particles to make their way towards the line of elliptical symmetry, but since its loose rubble (i.e. not enough gravity to maintain its shape), the individual rocks knock each other out of orbit. This is discussed in the video.
"Consider the three largest moons of Jupyter. Europa takes exactly twice as long as IO to orbit Jupyter, and Ganymede takes exactly twice as long as that. How can that be? This is an example of synchronization, but what's the mechanism? That's what this video is about: it's an explanation of something called orbital resonance."