This movie shows how a string doesn't moves in simple motion mode, like we would expect when a string is fixed by its extremeties, having the middle free to bounce.
Whenever one body vibe, it assumes a particular vibration due to its mass, dimensions and elasticity. But it doesn't moves solely in fundamental pattern, making a single bow in the middle. Every move that preserves its extremities fixed can stabilize on a string and this is called Harmonic Series, where one string will move in whole numbers fractions (as 1/2, 1/3, 1/4 and so on).
So a string really moves (vibrates) simultaneously in several ways, making 2 bows at 2nd harmonic, 3 bows at third harmonic and every multiples or partials of the main fashion. We can't see, but we can hear what this causes to Tone itself, because Harmonics can attenuate or reinforce the main movement (fundamental or first harmonic), changing the final or summed way string oscilates, making its tone to sound unique... And explains why matters where we place PUs (since each harmonic's peak of string movement is stronger in different places), as you push PU towards the bridge, you increasingly put it far from main bow and closer to the bow of one higher harmonic.
A simple tone is what you hear with a Senoid, the sound of your telephone tone or any simple electronic oscilator. Plain and boring. But natural sound sources always move in harmonic way. Whenever you hear 55Hz from your open A string, you hear also its harmonics (110Hz, 165Hz, 220Hz, 275Hz etc) and is the interaction of them all that defines Tone (not forgetting the fact that the body mass, proportions, constructive techniques and materials will also filter each harmonic, changing final tone as well).
It doesn't necessarily relates to the headstock configuration subject, since strings will be before the nut and supposedly will not interact with main string vibration. Tension is also a thing more related to string mass and elasticity (material and gauge) and shouldn't matter too.
I think that this choice 3+2 or 2+3 relates more with the way a string will bend before nut and how this changes string stiffness at the nut, how nut is forced sideway and downward and how effective the nut will isolate vibration at scale (desired) and at the headstock (undesired, since it will drain energy from string move).
My 2 cents: 2+3 seems better...
