I've played with fans/RGB controllers here since seeing the video - I can get to appear to the human eye, but only when the colour is cycling through to another - static colours don't effect it.
At a guess, it's the PWM of the fan being nearly in-sync with the PWM of the fan - but only briefly when changing.
If this is right, we could alter the PWM of the lights over a small range to make the fan appear to be spinning clockwise/anticlockwise intentionally - with finer control, to make it appear static.
Alternatively, we slightly boost the fan out of the PWM range of the LEDs when they're changing colour to eliminate the effect - there has to be a narrow range of frequencies that have a compatible ratio.
I remember reading about capacitor hum having it's lowest audible frequency moved outside of the human audio range in power supplies - the theory behind that is going to overlap here.
---------------------------------------------------------------------------------------------
Back to the case!
I like it - triple 120mm fans in the front. It'd be nice if there was the mounting option for twin-140mm fans too but they'd be off-centre.
Similar 360 front/ 120 rear radiator layout as the NZXT 450 - and it looks like there are slots up top for mounting fans? There's an unpopulated fan slot on the RGB controller that could come in handy here.