It is very buggy, and the UI is a nightmare.

E.g.: to play a video with an external audio stream you'd have to open teh files through this very specific menu (media -> open capture device -> switch to "file" tab -> click "show more options" -> when MANUALLY select teh files...).

There's no way to add an external audio when the media is already playing So you'd have to stop teh playback, and start all over again through that stupid ugly menu.

Like what the actual fuck? In most players it is as easy as a few clicks during the playback (usually something like playback -> audio streams -> add from file).