Check /usr/ports/multimedia, particularly the
driver(s) for the camera you might want to use...
....
Better to follow exactly what others might have proven
to work,
usb camera?
IP camera (many have their own embedded OS)
cctv camera (driver setup)
...
viewing programs, etc...
(a post below this one mentions /motion/...)
...
also the freebsd-multimedia mailing list for
reports/problems/questions (I think that is the
list, maybe others....
...
Once you get past the ports/hardware/driver
question there are the GUI (or) very complex
CLI to configure/setup...
...
Just spent a few weeks reading up. Too much to
begin to explain without a specific scenario, then
I would not be in a position to answer, other than
the above.