I heard this described on the radio that 'baby step guy' I think - a caller described it. The way it came across is this Medi-Share organization doesn't pay the bills - only the accounting. The 'each-month' share thing is really a direction to send a certain amount to "someone" in the plan to pay their bill (or part of it).
If you ask me it sounds like a Ponzi scheme or a chain letter deal....