OK, PHEW - easy fix for those of us that already downloaded it...
Go to Window, Movie Properties, Audio Settings.
The volume is mistakenly set to -Infinity (Mute) rather than the default 0db. Move the slider and the audio is there.
Chris, you'll still need to redo it though, obviously.
Jeff, you could also do this to raise your source volume - but of course you'd have to do it for each segment, each time. Too bad QT doesn't save it as a setting for each file.