Obviously, I'm not Step N Motion, but I think I can answer your question: it's my understanding Collage Video objected to the price discounts Cathe was offering on her productions (especially multiple-video purchases), which could oftentimes be better buys for the consumer than what Collage could or would offer. I think a line in the sand was drawn, and Cathe elected not to continue marketing her subsequent releases through them.
I found my first Cathe workouts through Collage (I-Max 1 and Body Max), and Collage is a great clearinghouse for a wide variety of vid and DVD workouts, but I highly respect Cathe for going her own route.
A-Jock