Only problem I see with this is if they are trying to stream multiple users from a single server/copy. For example, my app saves state (though you can choose to clear it to start over from scratch) so if you have been through part of a path before you don't HAVE to replay that. What happens when the next user comes along and finds half the game skipped, doesn't realize that, and chooses not to buy because they could play what was left during the preview time window?