I think Blockbuster is making money selling the pre-viewed dvds since they get them at a discount since they share the rental revenue with the studios. I don't think the studios foresaw them selling the dvds and competing with them. Each previewed dvd blockbuster sales is a dvd that a person will not buy new, cutting into the studios profits.

It will be interesting to see what happens when that deal expires. I think it expires soon. I think the studios aren't too happy about Blockbuster selling previewed dvds.