Easy way,

do a cat /etc/fstab

and look for the DVD entry... mine looks like this:
Code:
root@Morpheus:~# cat /etc/fstab
# /etc/fstab: filesystem table.
#
# filesystem  mountpoint  type  options  dump  pass

... snip ...

# Remaining devices
/dev/fd0  /floppy  vfat  defaults,user,noauto,showexec,umask=022  0  0
/dev/dvd /dvd  iso9660  defaults,ro,user,noexec,noauto  0  0
/dev/cdaudio /cdaudio  iso9660  defaults,ro,user,noexec,noauto  0  0
/dev/cdaudio1 /cdaudio1  iso9660  defaults,ro,user,noexec,noauto  0  0
/dev/cdrom /cdrom  iso9660  defaults,ro,user,noexec,noauto  0  0
/dev/cdrom1 /cdrom1  iso9660  defaults,ro,user,noexec,noauto  0  0
root@Morpheus:~#
Note that the entry for my dvd device is at /dev/dvd and a mount point of /dvd - the /dvd is what you would put in your setup for the dvd device... if that is what your entry looks like