IPA: /ˌdɒkjuˈmɛn.tər.ɪst/
KK: /dɑːkjuˈmɛntərɪst/
A person who creates documentaries, which are films or television programs that provide a factual report on a particular subject.
The documentarist spent years researching before filming the story of the local community.
Documentarist → It is formed from "document" (from Latin "documentum", meaning a lesson or proof) and "-ist" (meaning a person who practices or is concerned with something). A documentarist is a person who creates or works with documents, particularly in the context of film or media that records reality.
Think of a 'document' as a proof or lesson, and remember that a 'documentarist' is someone who creates or works with these proofs, especially in film.
No commonly confused words.