I'm worried now that Universal think it's to do with scratched / marked discs due to the packaging (or 'hand packing' if they insist) rather than a botched authoring of the DVD disc.
If they just sent replacement DVDs without correcting the authoring issue people will just have a second unplayable DVD.
No doubt there won't be time to correct this before the farewell gig, where I daresay they'll be flogging more of these sets with a disc that doesn't work.