In the film, a specialist from the BMW Classic Center says that the original 5 Series, which launched in 1972, provided the template for the BMWs that followed it that decade. Not only that, the 5 was the first to introduce the modern naming scheme that used the model number followed by displacement. Of course, the displacement part has gone out the window in recent years, but the formula remains roughly the same.
BMW's head of design from 1970 to 1974, Paul Bracq, also weighs in on the car he helped design. He highlights the shark nose as well as his focus on making the interior ergonomic. He also laments the limits of headlight technology at the time, which didn't allow for much design flexibility.
The video is a nifty overview on the origin of a luxury market staple. It also has some fantastic period footage of the car. You can check it out above and at this link. If it strikes your fancy, be sure to keep an eye on BMW's YouTube page, since more videos about subsequent models are sure to come out.