As he says in the video, they can't locate the position but can approximate distance from signal strength measurements.

To get location information would require one of the following: 1) An array of antennas pointing in different directions, this is certainly possible, but not using the single built in antenna in a smartphone.

2) The device to know its own location and to transmit this to the phone. This would only be as accurate as GPS and would use significantly more power.

Using signal strength to approximate distance is reasonable, but the location of the sensor, nearby objects and the design of the phone's antenna will all affect the measurements.