It looks like brasero is not able to backup protected DVDs even when libdvdcss is installed. I determined there is a one line patch in both debian and ubuntu to fix the issue, applied it to the package and verified it works as expected. the patch is located here: http://patch-tracking.debian.net/patch/series/view/brasero/0.8.0-3/006-fix-libdvdcss.patch IMHO, this should really go upstream, I don't really know why they didn't push for it (at least, I didn't find references of this in bugzilla.gnome.org)
Fixed in rawhide.