I saw some of these videos awhile ago. I think this women in an actual expert in the field of invisible stuff that kills you.
Yeah, she has a visceral understanding of the mathematics of exposure, statistics, and Alpha vs. Beta vs. Gamma, vs. Neutron exposure. Intensity vs. total source size, and duration. So just because the Geiger counter is chattering away, she's not necessarily concerned.
Radiation exposure has (rough) analogies to electricity, or light, when you talk about water hoses etc. Like how a Tesla coil or Van de Graff generator has a ton of voltage, but little amperage/current.
Radiation has several factors, intensity or counts per second/minute, the type of radiation, Alphas and Betas, stopped by just a few inches/feet of air, cloth, skin, paper etc. gamma photons and neutrons, very penetrating, or so energetic it can actually create secondary radiation. And the total source and area of exposure size has to be considered as well.
So you can have high intensity, but a tiny source, that's putting out Alpha or Beta particles that won't do much to you unless you hold onto it tightly for a long time, or ingest it, or a low intensity, large source of exposure that isn't generating lots of counts, but is giving off gamma or neutrons that could go through a few feet of soil.
Or of course, high intensity, large source, highly penetrating. Which would be something like finding the "Elephant's foot" in the basement of Chernobyl, or having a terrorist sprinkle Cobalt 60 stolen from a medical/food irradiation plant over your head.
And that's why there's
seven different main units of measuring radiation/exposure.
http://ieer.org/resource/classroom/measuring-radiation-terminology/And why someone like Bionerd23 does things that
seem strange or risky, when it's often the equivalent of the science professor touching a Van de Graff generator, and lighting up a fluorescent lightbulb with his hand.