If you have an analog wireless security camera:
It is probably operated on a 2.4 GHz frequency, the same frequency as video game controllers, microwaves, routers, etc. While not that big of a deal, those wireless devices can create interference. But they are susceptible to interception because analog wireless uses a consistent frequency, it is possible for the signals to be picked up by other receivers.
Digital cameras are more secure:
Digital wireless cameras work a little bit differently. They modulate their signal slightly, constantly cycling through frequencies in order to avoid interference. This also makes transmissions more secure. In order to pick up this video feed, a receiver needs to be paired with the camera. This means the camera and receiver are programmed to cycle through frequencies at the same rate.
Hope this helps, weenmeoff.
Cheers