The "match in a pool of Jet A1" demo doesn't really have much to do with the matter (and with a big pool on boiling hot tarmac in the July sun, it won't be me tossing the match).
And we're not talking about "a spark", we're talking about fuel droplets swirling around in the undercarriage bay and being ignited by arcing, not sparking, from the 115V brake fan wiring.
In my experience, 115V is enough for a nasty arc...
CJ