To: hooday
Hello,
First of all please make sure that you have the latest version
AVS Video Editor 5.1.
Also, please play your vob file in media player on your computer and make sure there are no audio defects.
If it does not solve the issue, please specify the origin of you vob file (is it home made DVD or standard DVD-movie). By the way, we usually recommend to open Video_ts.ifo file to load DVD.
Also, please specify which settings you select when convert to FLV and what player you use to play flv files.
Best regards.