Hi,
I see you connected it as I think you should. So the black wires should act as a 'Normally Open' and a 'Normally Closed' connection.
The sensor's power supply is rated 10-30 volts. Perhaps the 10 volts from the IoCore is not enough... You can try it with a 12 volt power supply, perhaps that makes a difference. Please make sure that you don't put a high voltage on the IoCore, so measure first what voltages come out of the sensor before connecting. Start with a 12v because this is probably safe for the IoCore.
So it should work with the outputs of the IoCore set to digital. But if above fails, you can try it with analogue. If you use it with the 10 volts as shown in the video we can set the calibration from 96% to 98% I guess... you will have to set the range to 0x3D6 - 0x3EA.
So for gpi1 that would be:
<gpi index="1" calibration="[0x3D6,0x3EA]">analog</gpi>
Then try the sensor with and without a piece of metal right in front of it.
Are these sensors expensive? If you want you can ship us one, and I'll have a look if we can get it working.
Greetings,
Bootsy