According to the AndroidandMe article, the SGH-T959 designation is similar to other Samsung phones that headed to T-Mobile, saying "Phones produced by Samsung for T-Mobile are always designated T-XX9." Phandroid adds that:
Another piece of evidence is an app called “Write and Go” that has a logo with T-Mobile’s trademark font, as well as T-Mobile’s MyAccount app. Finally, the icons for “Help” and “Visual Voicemail” definitely looks like they belong on T-Mobile phones, and an un-logo’d app called “TMO Contact” is a final dead give away.
In an update to Phandroid's story, one of Phandroid's readers mentioned that the phone might be heading to Thailand because "the native tongue of the video shooter is Thai, which would make Thailand one of the first Asian markets to see the phone."
The link to the Youtube video
was there, but isn't anymore. Sorry.
Image from AndroidandMe
Source: Howard Chui