OK, motors could have spindle play and other imperfections that could make the optical disk tumble a bit and introduce phase effects. Or, as WalterBright wrote, there could be resonances between the motors. Yet, all this tight feedback makes them control the acceleration and deceleration tightly. There is nothing analogue to how these motors are driven. Not an old motor spinning up at its own pace, it's all pre-determined by the motor controller. The motors precisely follows the pre-determined speed curves, from what I hear, similar to how a digital oscillator will. Plus, the envelope is digital anyway.
One of my first thoughts was: Cool, so I can touch the oscillators and skew the pitch! No, I can't. First, there's a cover. ;) But I guess the motor controller controls the pitch so tightly that the effect would not be musically interesting. Compared to when you put your finger on a vinyl deck, for example, which has much larger mass and often a much slower motor control, leading to these slow glides.
Apart from the fancy looks, I really wonder which interesting new soundscapes this instrument can make available. To me, this looks like a "normal" oscillator with ADSR control, just re-labelled as acceleration and brake parameters.