I have the same problem.
I just downloaded version 8.00 and am trying to drag and drop a mp4 file and capture the audio.
VideoPad converts it into a blank avi file.
I tried this five times, and it kept happening.
Was a solution uncovered? If so I haven't found it.
The mp4 plays just fine with an appropriate player.
I would love to upload the mp4 so you can check it out. How do I do that?