I have a strong hunch what's hiding in that glob of silicone sandwiched between the two blue single layer windings.
Pretty sure now it's capacitive.
Guessing this device has its roots in a transmission line
If my theory is accurate, those two blue coils are the two legs of a transmission line. The added capacitance between them increases permittivity which lowers the velocity factor, thereby allowing Nelson to strobe the transmission line while synthesizing a sine wave. He keeps distance between the two windings such that their opposing magnetic fields do not cancel, then draws off closely from the sides the magnetic field via secondary windings coated with ferromagnetic paste which aides in attracting the flux. This is likely the standard technique utilized in most all OU-like devices. Nelson stated using pancake coils was his preferred geometry--adapting this concept into a conventional transformer geometry would be quite challenging, though Nelson was successful at it in his first Radiant Box device.
Nelson is one sharp cookie; maybe soon we'll know enough of his tricks to be dangerous. In the meantime, consider the advantages of a delay line transformer--specifically how it is able to block counter EMF. Also familiarize yourself with the advantage of reducing the velocity factor for this application. Hint: The speed of light is what makes us pay for putting and keeping
energy in motion. If you can't put energy in motion and do real work with it while you go do something else, your COP will always be less than one.