You have to give your listeners this...
Those things are great. Had one when a teenager. Now days they cost too much but it seems like they were pretty inexpensive back in the 1970s
They work quite well. You can build your own with a light wood frame, some wire, and a variable capacitor. I made one a few years ago but nowadays, I'd be more likely to buy one, for the greater compactness.
It might be stating the obvious, but some viewers may not realize that, in the video, although the increase in signal strength on plugging the loop antenna in is dramatic, it's because that particular receiver has no internal antenna for the AM BC band at all. In other words, you're going from no antenna at all, to an antenna.
I think those little Tecsun receivers come with a small plug-in external antenna for the AM band. The tunable loop is almost certainly going to work better though.