While I can't speak on the European side of things, I'm reasonably certain that the power generated by US power plants is much higher than 120 volts peak-to-peak. More relevantly, the 120V that people talk about when they say that US AC power is "120 volts" is the root-mean-square of the actual value of the sinusoidal voltage waveform, which you get by taking the peak value of the waveform and multiplying by the square root of two (for sine waves, anyway). So 120 = V_peak * sqrt(2), from which you can calculate that the peak voltage is actually about 170 V. Furthermore, that is from ground-to-peak. In other words, regardless of what happens at the power plant, when the power gets to your wall socket it should be oscillating from about +170V to 0V to -170V and back.The generator at the US power plant creates a voltage that oscillates, going from -60V to 0 to +60V to 0 again, 60 times a second. At the European power plant its -120V to +120V at 50 times a second.
While as far as I can tell it doesn't actually impact the multimeter tutorial's effectiveness, I can see how that could lead to confusion and possibly unfortunate failures for people trying to make things that involve AC power.
Cheers!
Tcepsa
(P.S. In the future would there be a better place to put this sort of troubleshooting and/or a better way to go about it?)