Nonreadable (?) DVD and strange console message

["Thomas Mueller" <mueller6724%bellsouth.net@localhost>]

I have a DVD I can't read, so far I've tried with FreeBSD and NetBSD, get the 
message on mounting:

CD mmc 16, mmc_cur 0x80, mmc_cap 0xd3b

I mount with 

mount_cd9660 /dev/cd0a /cdrom  (/dev/cd0 in FreeBSD), run "ls" and get nothing 
at all.

But running "mount" by itself shows the DVD mounted on /cdrom .

Running df shows

Filesystem    1K-blocks       Used      Avail %Cap Mounted on
/dev/dk15      13910362    4401974    8812870  33% /
ptyfs                 1          1          0 100% /dev/pts
tmpfs           8357564          4    8357560   0% /var/shm
/dev/dk3      121863804   52260992   59853708  46% /BETA1
/dev/dk4      142191228    8022048  122793884   6% /home
/dev/cd0a       1832610    1832610          0 100% /cdrom

so there seems to be something on the DVD.  This happens in a drive capable of 
reading other DVDs.

This is the Seagate Business Storage installation-recovery DVD.

I haven't connected the Seagate Business Storage NAS yet, thought I'd first get 
an overview of the DVD.

I assume this would be a data DVD rather than a music/movie DVD.

I read "man mount_cd9660" but saw no hint regarding the console message I saw.

Tom