The probe is an NPN normally open (NO) sensor, and to test them, I used a 10K Ohm resistor (pullup) between the black (output) wire and +12v (which connects to the brown wire). Blue is ground - there is a good pic of the wire color scheme here. The pullup resistor brings the output (black wire) to +12V normally, and when the probe is triggered, it would drop the output (black wire) to close to zero volts, as the transistor inside the sensor would close the connection between the output (which is connected to +12V though a 10K Ohm resistor) to ground. The resistor is only for testing though, and not necessary when it is all connected up and in use (the resistor will be there still, but on one of the circuit boards).
So far though I like it, however the sensing distance was smaller than what was shown in the Nexi-Tech video, I had to lower it a bit more and could not use the 3.9mm plexiglass piece which was used in the video to set the spacing on the probe (see the pic). I was concerned that the bed clips may interfere with the probe, but they are far enough away that they do not affect it. I suspect it will be an upgrade over the old sensor (which was broken anyway).