You've been tricked.
Nah, I haven't. [...] I accept source code that's open to /me/ as a form of open source software.
Ahh, but the source code is not open to you.
RealNetworks have been careful to create confusion about this. While they have made *some* of the interface source code viewable (but none free), the codec module that is needed to actually play the RealPlayer audio/video is completely proprietary/closed/hidden/etc.