Hint: The above video still shows a simulated example of the phenomenon they share.

When you place a dense layer of fluid atop a less dense layer of fluid, it results in what physicists call a Rayleigh-Taylor instability. You can observe this effect in everything from salad dressing to lava lamps to evolving supernovae. Two-dimensional numerical simulations of the RT instability, like the one featured here, are used to study its properties.

FYFD explains:

The waviness of the initial interface provides a perturbation—a small disturbance—which grows in time. The two fluids spiral into one another in a fractal-like mushroom pattern. The continued motion of the dense fluid downward and the lighter fluid upward mixes the entire volume toward a uniform equilibrium.

[Thunabrain via Fuck Yeah Fluid Dynamics]