That's very interesting. It mentions courier service from the US, and a quick look on the VFS Global website shows this:I'm not sure if it helps anyone in this thread, but here's a scanned copy of the instructions given to me at the biometrics appointment in New York (yes it was actually printed a bit crooked). I don't think it's confidential, but any mods please let me know if this is not ok to post!
The link is to here: UK Visa Information - United States of America - User Pay ServicesImportant Information: Commencing 20 January, 2015 applicants applying for a visa to visit the UK can now purchase Return and Roundtrip Courier Service on this website. To learn more about these services, please click here.