I was actually the one who started CloneCD using .DVD files. Trouble is, I then progressed onto MDS and it stuck with .DVD.
Back then, DL weren't around and so there was never a need for the layerbreak value to be put in the file.
I will look into adding support for this newer type of .DVD file and it'll be in the next release.
Oh and you guess correctly, I can't give out the MDS file format info
So I'll start making these .DVD files along with the ISO files in DL mode, they won't be supported yet by imgBurn but sooner or later they will be, meanwhile we'll still enter the layer break manually or if you have clonecd i guess you can burn them with it, but i still think imgburn is better for this job.
He also mentions i can pass the layerbreak info directly to the program as an argument, however i think this is a bit out of the scope of _maker and perhaps mooGUI (or any new GUI being developed) is the right program to do this... you can determine the location of imgburn.exe in this reg. key