There was no internet, so unless you were connected to educational organization and their curriculum, there was no way to get information of various topics in somewhat palatable way. BYTE changed all that, and suddenly everybody could learn all about Prolog and Smalltalk and other Scheiße.
He was: he pointed out that the world of computing he (we) knew back then is illustrated in all the ads. Note that August 1981 is also the month the original IBM PC came out. In contrast the articles showed a world of computing with mice, overlapping windows, menus, cut/copy/paste.
A comment in the video pointed out that the mouse had been invented back in 1964 and claiming it was not common is a cop out. The author of the video didn't know about it before this issue and I didn't know about it. But now we knew, and for how many others was this true?