Well they finally said it, so now I can too! The Legend of Korra Bluray & DVD special features specify: "The Legend of Puppetbender Present "The Making of a Legend: The Untold Story" (original short) 'The Making of a Legend: The Untold Story' short features a comical look at the Korra characters, in puppet form, as they're interviewed about their adventures."
The next generation of Korra-themed Puppetbenders has lept from YouTube to Nick home video!
...Sorry that means you have to pay for it
But it's in Hi-Def!
And you won't have to suffer through YouTube ads!
Check out the press release here: [link]