Here is the deal:
I encoded a 15 minute piece of video that we digitised and edited ourselves to MPEG-2 using CleanerXL (later also experimented with Tmpgenc to see if that gave any other results, have not been able to burn that to DVD yet), brought everything in DVD Producer (Sonic) and burned it to DVD from there.
When played in our JVC XV-N33 DVD Player, the DVD seems fine. When played in it's older brother (JVC XV-S300) the audio and video are out of sync when the audio is LPCM Audio (1.5something Mbps) and when played using AC3 audio the video starts to jump ...

Now this is with Verbatim (made in Singapore) DVDs. When we use Raiteks the sync gap is smaller (with LPCM, haven't tried AC3)
We used to use Tayo Yuden but they are hard to come by so we had to use Verbatim, my suspiscion is that it is the media giving problems. Especially since it did work fine in my Philips DVD player at home (which is a bit older then the two JVCs )

My question is: am I right? or is there something else going wrong? We have ordered a set of others to check if the same problem is going to occur again... Please let me know.

The bitrate of the MPEG-2 file is set to 3000 min. 5000 aver. 7000 max. (to keep the video safely within boundaries) and thus a VBR encoding.