Look Dad, a SMART Surge Protective Device.

Gabriel or triggering electrodes are not really a new thing - but it is a very nice illustration for those unfamiliar.
The problem is that for a class 1 device there is a lot of energy to dump, so it almost has to be an open air arc, but that gives a very variable strike voltage and we need it to be low threshold and yet go off back to high impedance smartly after the event.  The sealed gas discharge devices on the 'electronics' module have a controlled amount of gas at known pressure and the internal electrodes are accurately spaced and that do not get oxidised or dusty. But being sealed, there is no-where for the hot gas to go, and a really high strike would leave you sweeping up broken ceramic and staring at splayed ends of wire. And, from experience, nursing a ringing in the ears.

So the MOVS and sealed gas discharge devices conspire to break over first, and to cause ionization around the tip of the starter/trigger/Gabriel  electrode.

(Sometimes referred to by the older HV pulse folk who use controlled spark gaps to fire high power lasers and so on as a 'Gabriel' electrode for long lost reasons that I suspect may be religious - the messenger that precedes and all that).

This little fog of ions around the Gabriel lowers the effective breakdown voltage of the main gap, which then breaks over promptly, and being in parallel, collapses the supply to the Gabriel driver and protecting it from damage.

As you say, neat.

Mike