The biggest problem with those CCTV systems is that once you configure the system to be accessible externally (or publicly on the internet with the ports opened), the security can be easily breached by known flaws in the firmware or software. Generally the software/hardware firmware is hardly updated and can be exploited.

No security is guaranteed but if I was to install a CCTV system, I would use network switches or camera's from US, Taiwan or Euro based companies.