The legal releases you need for a documentary film can differ substantially from the requirements associated with ‘commercial’ video projects. A documentary film has an ‘editorial’, informative, or educational purpose and is different than commercial projects. Selling or making money from your documentary film does not convert it to a commercial project. The United States First Amendment offers documentary filmmakers protection via freedom of expression.
The following link has various filming scenarios and answers depending on whether you are filming a documentary film or shooting video for a commercial project: -> Documentary Video Footage vs Commercial Video Footage: Requirements for Legal Releases