Once the frequency is captured (ie cloned) you can track the device, duplicate the signal and/or listen to a transmission.
That appears to be what he's attempting.
In the old days we called them 'bounty hunters', but in modern vernacular they're trackers. Guys/Gals who trace 'wanted people' for a living.
In this era the public sector track operations are high tech.
Start with an APLR hit. [Automated License Plate Reader] That initiates a track/trace opportunity worth $$.
In most homes there is a master bedroom. Most targets are found in this area within a residence.
Usually on the night stand, next to the bed.
In many cases (the really easy ones), the night stand will be located next to the exterior wall of the residence.
If the cell phone is near the wall, it's an easy capture. Only takes seconds. No-one even knows you're there. In/Out easy peasy.
This information can be sold, and/or used directly to collect bounty by working with police to identify location of target.
Currently (at least a year +/- ago) the private sector technology is still proximity specific. Meaning they need to be within a few feet for the capture to work.