I'm a lay person somewhat familiar with the terminology. I am going to be wrong on several details.

What they were talking about is phase weakening.

Think of voltage as 'electrical pressure'. Like PSI or Bar.

Think of amperage as 'volume per second' or 'amount of electrons (equivalent charge) per second'... like liters per minute.

Combine the volume per second by pressure and you get total energy per second; watts. Hence 'voltage * amps = watts'

Electric motors are also generators. When they spin they create their own 'reverse voltage', sometimes called 'Back EMF', that creates resistance in the windings of the motor.

The faster the motor spins the greater this 'back emf'. It'll increase until the 'back emf' creates enough resistance that it effectively negates the voltage coming from the power source. At that point the motor has reached it's top speed. This is why DC motors don't try to spin infinitely fast.

The strength of the motor, the torque, is directly related to the amount of amperage flowing. When the motor is at it's top speed it's generating only enough torque to overcome the resistance of the bearings and other parasitic drag. So very little actual current is flowing, especially in a very efficient motor.

Field weakening is a technique that you can use to overcome some of this limitation.

What it does is change the shape of the voltage wave. Most of the time on a oscilloscope it would show up as a sine wave or trapezoid... But if you can change the timing and peak of the wave then you can effectively weaken the magnetic field at the right time that the 'back emf' isn't as strong. Sort of flatten out the peak and make the pulse wider then it normally would be.

So you end up flowing less peak amperage, but overall more amperage. Depending on the type of motor and speed the amount of extra torque/amperage you can generate can be very significant. The trade off is reduced efficiency.

A simple motor surface mount magnet may only see a 20-30% increase in top speed and decrease in torque at the low end. A more modern interior mounted magnet (were magnets are embedded inside of steel laminates) that combines the strength of the rare earth magnets with reluctance of the magnetic field flowing through the steel.. (think of the magnets providing their own force at low end and then providing a guiding path for magnetic flux as the motor speeds up) Can see many multiples boost in top speed while still maintaining significant torque at low end. Field weakening on some motors can produce increased torque across the entire RPM range.

This is going to be very strongly taken advantage of in EVs like the Tesla Model 3.

Although in the case of most motors this field weakening is done electronically, by changing the shape of the waves sent to the motor.

This design does the same thing, but by moving the drum's magnets out of phase with the magnets on either side. So it's mechanical field weakening.

It's not a super-new concept or anything. I expect their patents have to do with the 'H' shape of the spindle and the math behind how it is supposed to work.

I don't know if mechanical field weakening really provides any real benefit over electronically controlled one.