In the a video from Peak Prosperity the claim is made that communcation between private individuals outside of the US government and an agency withing the US government can't be legally redacted under B5.
The FOIA website describes the B5 exemption as:
Exemption 5: Privileged communications within or between agencies, including those protected by the:
Deliberative Process Privilege (provided the records were created less than 25 years before the date on which they were requested) Attorney-Work Product Privilege Attorney-Client Privilege
Does the word agency here mean agency of the US government and thus communications with private individuals can't be legally redacted under B5 as asserted in the video?