miguel: I think Bastien has your ‘play this song’ api in totem already for Xine and GStreamer. He probably would accept a patch for a Helix backend if you want that. Another alternative to having to download your ‘160M’ of GStreamer is to have Ximian package each GStreamer plugin in its own RPM, that way you can download your mean, small and lean media framework with only what you want.
The problem with your idea is that as soon as you want to go beyond ‘play this song’ your solution would just give us a new media framework with plugins for the others, kinda like GStreamer today.