Currently the javafx.scene.media.Track class and subclasses aren't useful enough to allow for use of multi-track media, which is required to support alternate language and subtitle/captioning. Primarily it's missing a unique track ID that would be used by the application to selective enable or disable tracks. Rather than just adding a track ID property, we should give some more thought to how we're representing tracks to the client and open this up to the public for discussion. I'll list out options in separate comments.