I am interested in the question, how do you release a work so that it ultimately ends up in the public domain, but first make some money (perhaps a lot)? And how do you do this when your customer base is entirely aware that, in the long run, it will be available for free?
Back in the Eighties, Borland sold their Turbo Pascal development system for only $30 when competing products sold for hundreds, and did nothing in hardware or software to implement any sort of copy protection, while their competitors scrambled for complicated but unsuccessful approaches to combat piracy. Borland's approach to copy protection was simply the honor system, and making the product cheap enough that nobody minded paying for it.
The machinima Red vs. Blue is released serially as episodes. Those guys have an interesting approach:
Members of the official website can gain sponsor status for a fee of US$10 every six months. Sponsors can access videos a few days before the general public release, download higher-resolution versions of the episodes, and access special content released only to sponsors. For example, during season 5, Rooster Teeth began to release directors' commentary to sponsors for download. Additionally, while the public archive is limited to rotating sets of videos, sponsors can access content from previous seasons at any time.They are smart guys who have been doing this for years now, so it's likely they've hit upon as optimal a solution as is practical. Of course it helps that they have a great product that attracts a lot of interest. They are following the Borland approach: sponsorship is inexpensive and there is no attempt at copy protection.