The material is black in color and cannot be seen through with the naked eye. However, if you point a black and white camera at a sheet of Black-Ops Plastic, it becomes transparent allowing the camera to record whatever is on the other side.
What this means is you can hide a camera inside an object made of this special plastic and no one will know it is there. But the camera is free to record without having its view blocked.
The article doesn’t talk about the technology.