Your linked video confirms that the audio is there. So this isn't the flatline waveform/no audio issue that some others have encountered.
And the project linked earlier plays fine here in preview and upon export, using 8.63.
When you double-click your latest demo file in the VP bin (top-left), does it play?
Does the file play in Windows Media Player?
Is it silent only on sequence play or after exporting as well?
Did you test it in this release of Videopad? Retain you licensed installer and registration info, if any.