Question about radiation?

Not really.

Some of the original uses of radioactive material were for glowing paint. Radium and tritium can excite a phosphor (usually zinc sulfide) and that phosphor glows green. I suspect much of the idea of glowing green radiation comes from that usage.

In that case it is a substance that glows green, not an aura around an object.

If you have radioactive material in water, it can emit Cherenkov radiation. That will cause the water around the substance to glow faintly blue. It would be similar to the aura you mention, but it's limited to high refractive index materials (so it doesn't happen in air).

Finally,if the material were *really* radioactive (like, you'd be dead near it), it could be ionizing the molecules of air nearby. As the molecules recombine, you can get light. Mostly you get a purplish color that is seen in lightning and sparks. But you would have to have a huge radiation flux to maintain the ionization for a visible glow.

A geiger counter detects them you couyld convert the output from beeps to video.

some minerals scintillate that is they output a burst of light when irradiated

Once object is warm it is death yet. And so any light.