I am still not very clear on what you are tyring to do, but if I understand you correctly ....
Th SONY HDR-SR12 is a High Difination video camera, using a Hard Disk as a recording medium, and saving files in mpeg4 format (for HD) and mpeg2 (for SD)[which the "One Touch" program reconizes.]
When you export these files to a computer and create a DVD out of them, the files on the DVD are of the vob format. If you import DVD video from a DVD to a camcorder, it won't automatically change into mpeg2 - you need a conversion program to convert them first, but then you would lose details - they would not be exactly the same original mpeg2 files. For this reason, the "On Touch" won't reconize the vob files you put back unto the camcorder. But....where are the original files ? They should still be on the camcorder Hard Disk (if you have not reased them) or on the computer hard disk where you saved them to "author" the DVD.
OR are you trying to save a DVD from another source to the camcorder ? If so, you won't be able to, for the same reason.
(I have no experience with the SR12 nor the "One Touch" program)