What if you could save your score / midi file to YouTube? Would you use this feature or add-on application?
The MIDI file is encoded into video then uploaded.
To give it to someone else, you would give them the link to the YouTube video. They could then playback that video and a player with the right kind of decoder in it can decode the video back into midi for playback or editing.
A couple of advantages are the people know how to share videos, but not midi files.
Another is that the video can also have normal video that is played in sync to the midi playback. This is similar to Disklavier.TV.