Links:
The Essential Mix:https://www.youtube.com/watch?v=ycFxOhLZYFw
My favorite recording of the song on YouTube, directly lifted from the research without the announcer's voice added: https://www.youtube.com/watch?v=por5SopwHDc
Part of the original recordings, actually a different song recorded at the post office by the same researcher. This is also a fantastic piece of music! https://repository.library.brown.edu/studio/item/bdr:146670/
Some kind of weird search results which contains links to nearly a dozen videos, some of which are the song from the Essential Mix, including some with and without the announcer's voice, and also other recordings including other tracks from the original recording and also part of a documentary that I guess goes back to the same post office, which doesn't have quite as good a song but the video of the mail sorting is neat to see. https://wn.com/ghana_post_office_workers_music
The page on WFMU which apparently first spread this recording to a wide audience by mentioning the World Music CD. Includes a link to the first YouTube video. http://blog.wfmu.org/freeform/2005/12/work_song_from_.html
From the WFMU page, a student's fact sheet about the recording, created as part of a school project. http://faculty.weber.edu/tpriest/FacetsMdl_files/Postal%20Workers.html