Here you see first the figure 8 with the 88 inside. Than you see it get a 90 degrees corner witch makes it turn in to 2 cubes.

All movements are fluid. Than you see the 3 rings octahedron or cube core in this form it is not possible to get from one ring to the other in a fluid movement. So you have to split it in to a cube to be able to go in a fluid movement tru the 90 degrees 8 from one ring to the other. The cube can flip and turn by taking a diferent path tru one pair of rings.