Back in the days of film, there was a type of photography called "infrared photography," wherein photographers used infrared film (which picked up near-infrared light, but not most visible light) in combination with an infrared-pass filter on their lens (which blocked out most visible light, allowing only near-infrared and infrared light to pass). The resulting look is surreal and otherworldly. Some examples are found here: http://www.pbase.com/yp8/some_bw
In the digital era, infrared photography enthusiasts have to use different means. Most digital sensors are capable of picking up infrared light, but camera manufacturers place an anti-infrared filter in front of the digital sensor, because allowing this infrared light to hit the sensor causes blurring, lower contrast, and other generally undesirable effects. Today's infrared enthusiasts often mod their digital cameras by removing this anti-infrared filter from the sensor and placing an infra-red pass filter on their lens, thus creating a digital version of the old film + filter set up.
This is likely what was going on behind the camera you mentioned. Art, not science.