I've been following this guide to mux the 2 languages together into an mpg:
https://www.videohelp.com/bbmpegedit.htm

I've been doing exactly as the guide says, however I can only play the first audio, but not the second for some reason, do I need a codec or something to play dual audio mpgs? I've been trying to play it in MediaPlayer Classic. Any idea on what I'm doing wrong?