Depends!
My problem with tab's location is because it sucks in text tutorials/help texts if the item you're starting which is not there. Happens to non-D4 users (+50D). No problem in video tutorials or in workshops: You introduce the topics and with no real effort you start with second (in modern cams: first) tab's content and most people will just be fine.
Text books/tutorials are a different thing. It's a major PITA for writers and readers if the introduction has to begin with some kind of "if-then-else" or explain why things are not there or other way round. It's just a bad start. Call it "didactic" reasons.
Beginning with "Expo" and "Overlays" is actually convincing: It doesn't matter if you're into stills or video, comes handy for both. And Expo even starts with terms you are familiar with. Big win!
Now, *after* you made people happy you may introduce something not so straightforward and - IMO - placing Audio after Movie makes sense because it's related to movie.
Yeah, not the strongest use case, I know!
