I know this post is two years old. However, I wanted to point out that I had this problem and solved it if it helps anyone out
The problem still occurs even if you do
#mount -t cd9660 /dev/cd0 /mnt/dvdrom
.
Having used Solaris at university over a decade ago I have basic UNIX experience, but no knowledge of FreeBSD or any other non-Windows(r) OS. I immediately started walking my way through
man pages and trying basic troubleshooting steps. I tried searching the 'net for my problem, but found nothing.
After a long chain of troubeshooting logic I won't reproduce in detail here, I realized that
/proc was not mounted.
It appears that
mount
won't work properly if
/proc is not mounted, but I didn't investigate any further as
I'd solved my problem (I may well get curious later and go and look at the source to find out how
mount actually works in FreeBSD)
I did
#mount -t procfs none /proc
after which
#mount -t cd9660 /dev/cd0 /mnt/dvdrom
worked. I then added
/proc to my
/etc/fstab and have not had any more problems - the installer does
not do this for you; it's perhaps very Windows-user like for me to expect that it should
I am running on an old version of VMWare (can't upgrade due to CPU not meeting requirements) so YMMV, but I hope this helps someone as I was unable to find a solution by searching the 'net and had to use my own brain

~M