Not really. The proper subtitle for this film is "The True History of Dungeons and Dragons", and the story that it presents is largely about who 'really' invented D&D. But to answer that question, the film spends most of its time in the basements of miniature wargamers. Gygax doesn't make an appearance until almost the third act. Which means that most of the movie is about how a few scattered groups of wargamers coalesced in the Twin Cities area in the 1960s, and how they managed to cobble together a hobby out of little more than a few kid toys, a bit of felt, and a lot of really smart reading of musty old military history books.
It's a great look at the earliest days of our hobby, and includes a lot of familiar names. It's worth a look. I rented it on Amazon, but you can go straight to the producer's website here:
https://www.secretsofblackmoor.com/