Near infrared is effectively just light, and there's not a whole lot of it. It's not infrared from heat, like you are assuming. Near IR is generally up to 1400

Near infrared is effectively just light, and there's not a whole lot of it. It's not infrared from heat, like you are assuming. Near IR is generally up to 1400nm wavelength, where the infrared from heat isn't really a factor til you hit 4000nm. The intensities of NIR are too low to be worthwhile. The scientists made something that could see your remote control's LED, not your body heat.