It's not new; in the 1950s MI5 were tracking diplomatic and spy transmissions using the same technique - codenamed 'RAFTER.' It's also how TV Licence detection is carried out in Britain.
What the lady didn't state was that with some software these devices can be made to track aircraft by exploiting their S Mode transmissions on 1090MHz.
These devices have a range around 25 to 2000MHz but you can build or purchase a converter so you can look at lower frequencies and there's a lot of exploitable signals around 300 to 500kHz as well as 10.7 and 21.4MHz.
You can even listen into baby alarms on 49MHz - not that I would ever condone that.
As a Sunday Times journo intimated in 1989, if you turn on an electronic device you just shout out your details; there's a lot of persons wanting to hear them.
We are just listening to short wave radio broadcast transmissions, AM and FM broadcasts, ham radio, and pirate radio transmissions. I have no interest in what she is doing. I don't have time to listen to noise.