VP isn't the problem; there are two tracks and Videopad prompts for which to load.
But the first is silent - even in a media player. Narration is on the second channel. Create the MKV again, complete with game audio.
When it's added, chose channel 1, then drop the clip from the bin onto the timeline.
RE-import the same file, but this time chose channel 2, and OVERLAY it just below the other clip.
Now you have two channels mixed, and can control the volume, effects and muting of each independently.
Once you have a complete MKV file, upload it again here and someone will check it out.
