A crazy cycloidal gearbox for 3D printing. Georotor.

What the heck is going on inside the cycloidal pinion?
This video can help you to understand what is going on.
The pinion has n1 theet and the internal gear has n2 external teeth.
In the first video:
pinion: w0
internal: w1=w0*n1/(n1+1)
external: w2=w1*n2/(n2+1)=w0*n1/(n1+1)*n2/(n2+1)
Second video has identical angular speeds but we have displaced the center of the external gear.
Third video, we have fixed the angular speed of the external gear to 0:
external: w2'=w2-w2=0
pinion: w0'=w0-w2=w0(1-n1/(n1+1)*n2/(n2+1))
internal w1'=w0*n1/(n1+1)-w2=w0*n1/(n1+1)*(1-n2/(n2+1))
So the ratio is (1-n1/(n1+1)*n2/(n2+1)):n1/(n1+1)*(1-n2/(n2+1)). A piece of cake, isn't?