But you could add a second camera somewhere in the screen. Cameras can be very small.
Small is as small does.. . and costs. To collect any light the opening would have to be sufficient to allow enough light to excite the sensors. You are talking about a camera that would fit between the display pixels of your computer or mobile device. It would require lenses and a. CCD sensor of some complexity to resolve any detail at all.
On a 22" monitor, the standard pixels per inch is about 200. . . But those are composed of three actual LED lights, so your hypothetical camera lens would have to be smaller than 1/600th of an inch in diameter. . . Or you’d have a distorted color pixel. . . Perhaps a dead pixel. You’d also have to have considerable circuitry on the matrix of the screen to handle the CCD plus graphic RAM and a radio of some kind to transmit the data, or an open port if using the internet, not to mention processor time which would be noted. It’s not. Ergo, this hidden camera simply doesn’t exist. By-the-way, the sheer cost of such miniaturization would likely dwarf the cost of every other component in the computer!