I don't have an answer for your sound problem but you can save on DVD's by burning your project to a folder. This creates a folder on your PC containing your project exactly as if you had burnt it to DVD. You can then play this DVD with a software player (e.g. PowerDVD, Windows Media Centre, VLC Media Player etc ...).
When you are ready to test your project on a DVD Player use a rewritable DVD first (most modern players can cope with DVD+RW & DVD-RW).
Insanity is hereditary, you get it from your children
Welcome to the forum.
I could not find specs. on this camera, so you will need to help us a bit with the specifications of the resultant footage.
Probably the easiest, especially since the footage was captured from another program, would be to download the free utility, G-Spot, and run one of the files through that. It will tell you the full specifications. To save you a lot of typing, just do a screen-cap of the G-Spot screen, with the file loaded in.
Most JVC cameras capture in a proprietary format, MOD for SD footage, and TOD for HD footage. These can cause problems with PrE, though usually with Import. Still knowing the full specs. of the captured files will go a long way to solving this mystery.
Now, a few questions:
1.) can you hear the audio, when you play the Timeline in PrE.?
2.) have you added any audio, say MP3 soundtracks?
3.) what brand of blank media have you been using?
A note: Neale's suggestion of Burn to Folder, as a test, is a good one, as that will take the blank media out of the equation.
4.) with your test DVD, have you tried playing it on both a computer and on a set-top DVD player? What is the result of both tests?
Good luck, and we look forward to hearing the answers to those questions