The main reason we can't release Flash Player as open source is because there is technology in the Player that we don't own, such as the industry standard hi-def video codec, H.264. Adobe pays for that codec so video plays reliably worldwide, across browsers and OS's. So we make it as open as we can - by releasing the specifications.
http://blogs.adobe.com/open/2010/02/following_the_open_trail.html






