What I think was meant when this was writen, is that currently only single layer DVD-R are availble. thus if you want to back up a DVD that is duel layere (DVD-9) you can't unless you compress it to fit a single layer disk (DVD-5) or split it to two discs. However technology has preveailed and this should be up dated. There now are DVD burns that can write to duel layer DVD+ disks and the minus camp is still working. See http://www.afterdawn.com/news/archive/4552.cfm that should clear up some things for you.
