Having looked at the video again, it's evident that the heating mats are switched through a contactor, which can clearly be heard just after the thermostat is turned up. One thermostat for the whole lot most likely.
From the rate of flashes on the meter, the heating load is approximately 8kW or 35 amps, far too much for a 20A MCB. Not exactly suitable for a 32A device either.
For 60m² that's about 133W/m², close enough to the typical 150W/m²
29 flashes in 4 seconds of video
x15 = 435/minute
x60= 26100/hour
that meter is 3200/kWh
26100/3200 = 8.15kW
Less whatever other items were on at the time, likely virtually nothing based on there only being 2 meter flashes in 7 seconds before the heating was switched on.
problems -
If the wrong 20A MCB was installed and then just changed to a 32, is the circuit cable suitably sized for that load?
8kW is overloading a 32A MCB
With all heating switched from a single thermostat, there is no diversity
8kW of heating will cost about £1.30 per hour to use, just 2 hours a day is £1000 per year.
Tails from cutout to meter and out from meter look significantly undersized
It's a looped supply, which is very likely limited to 60A, or even less.
Contactor not visible, but may be the box visible at the end of the video on the right side with the collection of black wires dangling down.
FCU probably just for the thermostat and contactor, not the full heating load.
