Automatic live quality switch between sources [MPD File Player]

I suggest we could have a new way to store video files: as local mpd files. That way we could direct play multiple resolutions with automatic switching.

The functionality should already be in plex to play their sources, this would be just enabling it for users.

In no way I am suggesting support for encrypted files or mpd files that load from another server. I just think it would be neat to have that for local files.