Or how it works at all. Is it like a shallow ground-penetrating radar? If not, how does it find these sites? The article left more questions than it gave answers.
It's just LiDAR.
They manipulate the data on a computer to explore the landscape (digitally removing tree canopies and things like that)
While you're technically correct, I think calling it "just" LiDAR is kind of underselling how amazing that technology really is!
It's LIDAR. It's main benefit for finding archaeology earthworks is that it is possible to remove the vegetation from the results. So anything obscured by trees becomes visible for example.
MSM - even the BBC that are supposedly a bastion of good journalism - are generally terrible at covering science. My theory is that journalism now pays so poorly for most in the profession that all the decent graduates seek work elsewhere.