Your CCTV camera most likely has a "composite video" output on the phono-type connector for video, and line-level audio output (although a bit rare for a CCTV camera to also have a microphone to provide audio).
You would need a video analog-to-digital converter box like one of these to interface to your Powerbook:
http://www.canopus.com/products/videoconversion.phpThese converters connect with the Firewire port on the PB, then you can use iMovie to record and play the video. Be aware that iMovie uses 13GB of disk space per hour of recording, although you can compress that file into a much smaller Quicktime movie afterwards.
15" std rez AlBook 1.67GHz, among others Mac OS X (10.4.7)