I did some experiments. Seems that a spotlight ignores objects close to the light. So, a spotlight set inside a screen works fine, even with shadows on. Moreover, shadows are required to get a resonable effect, IMHO.

I came out with a good effect if I attach the same picture I have in the screen to the light (kind of image based lighting). But, lower the images intensity to 0.5.

Play with the lights distance parameters. Also the angle width limit (160) can be removed. If you don't know how: Double click the parameter and insert a new value for maximum.

Below is a sample picture. All boxes/spheres have materials "out of the box". There is one pointlight (40% intensity) to illuminate the scene. The rest is from one spotlight attached to the monitor. The whole scene (including the TV-prop) can be downloaded from here

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