3rd party streaming services such as Netflix, Hulu, Amazon Prime, etc. have account license agreements that preclude streaming media from those services, even if copyright exemptions such as fair use would normally permit such streaming.
Netflix does allow a user to stream certain documentaries from their service for educational screenings. More information on which documentaries can be streamed and restrictions can be found on this page: https://help.netflix.com/en/node/57695
An instructor with a Netflix account can search for a specific documentary on this page to determine if it can be shown in a classroom: https://media.netflix.com/en/
For example, the documentary "Knock Down The House" is available for streaming- this is indicated within the synopsis under GRANT OF PERMISSION FOR EDUCATIONAL SCREENINGS (see screenshot below)
If a film does not grant this permission, it cannot be shown in the classroom due to the license agreement the user has agreed to previously whent signing up for their Netflix account.