This is an excellent example of thermal blackbody radiation. I especially love when they squeeze it the second time, and you can see it blowing out high energy radiation in the visible spectra. Somewhere between electric arcs and lightbulbs blowing out.

This sparks were radiation?!

follow up question: why the FUCK are they so close to that

Radiation doesn't unilaterally mean "murdering you" radiation.

Heat, the visible spectrum of light, and radio waves are also forme radiation. The radiation you're thinking of is ionizing radiation. Beta, alpha, gamma, and x-rays.

They're probably close because the type of radiation they're dealing with is non-ionizing radiation and in this case specifically probably light and infrared