In old days there would be little vibrating hammers mounted to the side of them to 'unstick' them automatically. And that 'low power arc' is actually a few thousand volts across an airgap of a couple of millimeters, the EM from that is massive.
For an encore: you can pick up lightning strikes with a long piece of rebar overwound with insulated copper wire stuck into the ground (so it's vertical). Every 'click' you pick up is a lightning strike somewhere within a few thousand km from where you are, louder clicks are closer or more energetic discharges.
I built one of these when I was a kid with a piece of plastic tube, filled with filings from an iron pipe and two metal pushed into either side. I tested by clicking the electric started on the stove and flicking to reset, I was amazed when it actually worked.
I was wondering when watching the video if Mehdi's supposition about an oxide layer is the only thing at play or whether there could be a layer of air instead / as well?
I've had cheap battery operated devices that react in the same way when a lighter clicks near them. Except they stay turned on because the first thing they do is latch their power on.
And this is certainly one of the few things on his channel that I can try at home!
The wikipedia article -
https://en.m.wikipedia.org/wiki/Coherer