If those two black wires going from your chassis are the ones on your "AC 1" on your power supply (it appears so), then what's happened there is he has just used the power supply's terminals to connect the monitor's power wires to the plug. If this is the case then the power supply isn't doing anything to the monitor, merely the terminals are connecting the monitor to the mains. So if the plug is getting 220v, so will the monitor. Changing the power supply switch to 110v/220v only changes its own operation (for gameboards, lights etc.) and the monitor is still 'directly' connected to whatever voltage the mains is.
I'm not sure of your particular model, and google is lacking, but my 25" Wei Ya chassis is 110v only, but if i remember correctly does not require an isolation transformer. I hooked it up to one anyway to be safe. It seems that the setup he's used would be fine if the mains is 110v but in your European country, the monitor is getting 220v instead and there begins your problems.
You could either get an isolation transformer to provide the 110v for the monitor from your 220v, or you could run the whole machine on 110v through a step-down transformer. Remember to set the power suppy's voltage right too

EDIT: Corrected information on my own model, it's been a long time since I installed it!