The phrase "a documentary about how to" is correct and usable in written English.
It can be used when referring to a film or video that explores a specific topic or provides guidance on a particular subject.
Example: "The documentary about how to reduce plastic waste offers practical tips for individuals and communities."
Alternatives: "a film on how to" or "a documentary focusing on how to".
The studios would put out a four-hour documentary about how to garden tulips if they thought they'd have a $100-mil 100-mil opening.
But the network produced a documentary about how the American Society for the Prevention of Cruelty to Animals helped pets and humans deal with their losses on Sept. 11.
A10 Religion Journal The absence of a description of Jesus in the Bible has spurred imagination, a fact made vivid by a documentary about how artists have rendered him to be broadcast on public television stations on Easter Sunday.
In an interview with USA Today, Groening was asked if he had anything to say about the row, which started when Hari Kondabolu – a standup comic from New York – made a documentary about how the character was used to bully him when he was growing up.
* "HATE.COM: EXTREMISTS ON THE INTERNET" A documentary about how hatemongers have used the Web to find new recruits, spread their messages and in some instances even set up hate crimes.
The result is What Happened To Her, a documentary about how murdered women are depicted on screen.
Getting Up, a documentary about how graffiti artist Tempt One gets back to making art after being stricken with a disease that leaves him virtually paralyzed, is an exceptional story crafted into an exceptional film.
Then, early this year, he released "Carnauba: A Son's Memoir," a documentary about how he retraced a trip his father took to Brazil in 1935.
Tenement Museum: Popcorn with schmaltz (chicken fat) will be served at a screening of "Welcome to Kutsher's," a documentary about how the traditional foods of Eastern European Jews were served (and preserved) with American abundance in New York's borscht belt resorts.
