FLV Player, Split Audio Streams

Okay, you know the typical video you find on youtube? Well I want an FLV Player that has the option of turning off a seperate audio stream. For example, let's say the video was of someone going page by page, of a book. Now, some people would like it read to them, or just have some nice background music. Would it be possible? To switch one off? Because I'll be making a series of video tutorials, and I want the end user to be able to turn off or on, narration. I would think that it would have to be done with 2 files? The video file and the audio file? Or could those be in one file, and split somehow? Taken from this post, this is pretty much what I wish to be acheived. [login to view URL] "I want to make some videos where I put a backgorund music track on it. The other audio will be a person talking or what ever. But What I want the use to be able to do is, turn off this background music if they want to and just hear the person talking. On an flv player I suppose what im after is 2 audio buttons. Can this be done - or is there another way of doing it, maybe, you have both running but you can turn the other down to 0 achieving the same thing .."