Hi there again Gerald,
I'm very happy to read you are still using AVStoDVD to create educational DVD for your students.
About the issue, have you tried simply changing manually the avg video bitrate:
- 'Edit Title'/'Video'
- toggle off 'Auto Video Setup' and 'Auto Bitrate'
- change default bitrate as you want
Doing that, you will get also legal output size decrease/increase and the cop "Target Video FileSize" will let you pass.
Let me know
Bye