Ok, picking this back up after a year and a half because innovation has brought us here.
If you click on some of the videos in the sidebar of YouTube when this one plays (or if you've selected AutoPlay), they'll get into discussions of Reynolds number, which is a ratio of laminar to turbulent flows. (actually, that might be backwards - Reynolds Number is expressed as a whole number rather than a ratio. 400,000 rather than 400,000:1)
Ron's described vortices being created by the groove since the beginning, now we have Juan Reyes' TB taking that a step further, generating microvortices PREGROOVE that seem to enhance it. I'm speculating along the lines of tossing more of the mass of laminar air into the airflow headed for the groove, sooner..."stoichiometry" of (for?) "gasoline" being 14.7 masses of air to one mass of gas.
I'm no physicist or aerodynamicist, or heck, even any kind of scientifically-based engineer, but from what I can tell, we're making the inertial energy of an incoming (laminar) airstream much more kinetic (turbulent) with the groove (and these vortices), and that makes our engines more powerful and efficient and clean. so if the little dimples make lots of little vortices of air move, the groove (a big, specifically-shaped dimple) must make the energy of the air mass from those wee vortices REALLY kinetic, or really turbulent, or have a really high reynolds number.
Yes, I'm sure somebody's saying "wait...doesn't more air mean more fuel for more power?" Remember - we're not putting more air into the system; we're just making what's already there do different things and that means we get different results...(better results than the factory designed, it turns out). It seems that the answer to "why does the Groove work" is if we break up the smooth laminar air into more turblent air, we are possibly mixing atomized/vapourized fuel better than it has before for a possibly denser, more evenly mixed air charge. And that's not even talking about the other parts of The Power System modifications, or taking them into account.