
There is a movie called Art & Copy I'd suggest watching - it's currently available as Watch Instantly on Netflix if you have a subscription. It's about some of the heavy lifters in the advertising and design worlds around the time design started to become more acknowledged as being important to advertising.
The other movie is called Helvetica (also available on Netflix). It's about, you guessed it, the font Helvetica. It's more of less split into the "Helvetica is perfect for everything" camp and the "Helvetica is fine but there are other options out there" camp.

Both movies are good but I personally felt more inspired by the Art and Copy one.