Problem solving day I think. Needed to make a copy of DVD on FreeBSD. Used the command:

growisofs -Z /dev/acd0 -dvd-video /path/

But this aborted with:

:-( unable to CAMGETPASSTHRU for /dev/acd0: 
Inappropriate ioctl for device

It appeared I had to do two things: make sure the atapicam driver is loaded and when done, use the proper device, i.e. the cd not the ac0 driver:

kldload atapicam
growisofs -Z /dev/cd0 -dvd-video /path/

Loading this driver is best done at boot in /boot/loader.conf where I also enabled dma:

hw.ata.atapi_dma="1"
atapicam_load="YES"