I think 'slow walk' really optimizes dance forms intention to not only act as an accurate 3D notation for a choreographer, but also to encourage the developments of new movements or choreographed dance sequences through its viewing. To slow a natural movement (like walking) to such a degree that you might then see it totally differently, that you can then rethink, and recreate from that breakdown is really interesting.
As you watch the slow steps of the 3D figure walk, you notice a shift of weight as she moves from foot to foot, her head swaying to look over the leading foot in the exact same time it takes for her to perform her next step. The slowed nature of the clip makes this noticeable, this can then be elaborated/enlarged or even totally removed by the time it is taught to the dancers. These movements and their developments may well be missed without the use of this tool.

I think this tool also saves choreographers a fair amount of time.(Even though it is initially difficult and tedious to master) Instead of having to make fast decisions in the rehearsal period that will ultimately affect the look of the piece, the choreographer can get a very precise idea of how he would like the more intricate movements and moments of the dance to be performed. This puts the choreographer in a stronger position when translating it into performance,as he really knows just what he is trying to achieve. It allows precision rather then a lax trial and error system that may waste allocated rehearsal time.