That would only work for cameras in B/W or "night" mode. Most decent security cameras have a movable IR filter. In color mode, this IR filter is moved into the

That would only work for cameras in B/W or "night" mode. Most decent security cameras have a movable IR filter. In color mode, this IR filter is moved into the light path to filter out infrared light. IR light causes a purplish tinge to color video, and the easiest approach is to reduce the IR light hitting the sensor. In night mode, the camera drops the color processing and just yields a B/W image. In this case, the IR cut filter is moved out of the light path, allowing the ambient IR light to hit the sensor and provide more exposure ability than you would get from just the visible spectrum IR light.