Roman, thanks for the provided info! Actually I don't need theoretical knowledge for Silverlight implementation - I have already done 4 different container parsers/demuxers in managed code.
Now I have very specific task: I need to adapt my managed HLS solution (worked perfect on WP7/WP8/desktop) to the Win8/WinRT.
As for joining your project: thanks a lot for offering but I'm extremely busy now, not only with my job but with my home-brew projects (check marketplace for SeNSSoFT). I'm so sorry but can't join right now (may be later?).
BTW, C++ isn't that terrible ;) (but I'm not touched C++ last 3 or 4 years - should work on C#). But I agree - MediaFoundation code and concept are very complicated and le me say kinda outdated (c++ samples looks like a 10 years old Direct Show samples).
I prefer Silverlight concept - very clean and easy to understand.