Security spy cameras are used for video surveillance without advertising its presence. The regular sized CCTV security cameras have a deterrent effect because people tend to behave innocently where surveillance is known. A portable mini security camera allows capturing people acting naturally and behaving candidly, and sometimes illegally. The nanny cameras are utilized generally when the chance of illegal behavior is greatly anticipated and confirmation or evidence is needed. To make a spy camera truly mobile, you may need a mobile DVR and a battery pack. While a hidden surveillance is very effective, it is also a privacy liability. Please check your local regulations before its intended use.