The concept of that service bases upon the Creative Commons as they are described here:
http://creativecommons.org/about/licenses/So, if you make e.g. a game free via SellYorRights.com, you can mix from the 4 attributes: attribution, share alike, non commercial, no derivative works. Now, if you would for instance DON'T use "no derivative works", you would let others modify, built upon it. If you would use "no derivative works", you would let others copy, distribute, display, and perform only verbatim copies of your work, not derivative works based upon it.
So there is no explicit need for open source. If you just distribute the binaries - that is no problem. If you would provide the source, but you would have to have A7 pro to compile and run it, there would be no problem. But in this case, another one could take it and "port it" to the free Lite-C version for instance or to OGRE or iPhone...
I dont really like the "real" open source idea of GNU for example because it doesn't really fit on authoring suites like Gamestudio. There was a nagger who complained very much that I distributed the RUDI source under GNU but you are required to have Gamestudio to compile and run it. That was one of the reasons why I wasn't to much interested in keeping it updated after the release...
Also, that SellYourRights.com concept could be nice for intermediate staged developing of games, too. If you would release very often intermediate stages of the game (alpha, beta versions) - you could for instance spend money on cool graphics and promote the next release with screenshots, movies and so on but you only keep on developing, if enough people fund e.g. the costs of the new level.
I am really interested how they manage to make the service available for software and more important: games.
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