Pretty cool watch. Probably old news by now on any serious scale though.
He basically isolated some low frequencies (which means they penetrate materials well) of plane engines and calculated based on a few of them a precise location where the video was taken.
They go through this in the video. The frequencies in question overlap with large portions of the vocal range, so not very practical. They also show that it’s pretty easy to recreate the data even when it’s attenuated.