What is this "Tateau-plugin" and where can I get it? It
looks interesting.
Did you try VirtualDub's
Alias Format filter,
Color space=(same),
Range=Limited.
This tells VirtualDub to expand the range when converting to RGB internally, without an extra levels conversion step.
Use VirtualDub's
Levels filter,
Show preview,
Sample frame to view a histogram within VirtualDub.
How are you exporting frames - with PNG or TIFF images I assume?