Seems like they simply copied this 1998 experiment: "Peroral gene therapy of lactose intolerance using an adeno-associated virus vector", https://www.nature.com/articles/nm1098_1131
In addition to most of the substantive details, the screenshot of "Fig. 2" shown at the 4:45 mark matches Figure 2 in the HTML version of the paper at that link. (EDIT: Screenshot seems to be enlarged clip from the PDF at https://www.nature.com/articles/nm1098_1131.pdf)