You need 3 things:
1. A camera that makes good enough images even in the dark.
2. A device to record the movies.
3. A device (PC?) with software to review and manage the recordings.
Either #1 or #2 must be smart enough to only make a image or store the image when needed (that's the motion detector part). And it makes sense to have that in #1.
I'd find a company to install this according to your needs. They can advice you on the hardware and software you need also.