"Private.rar" is not a specific commercial product, movie, or book, but rather a used for compressed archive files. Because it is a common name, "reviewing" it depends entirely on where you encountered it.
: Typically refers to rare CD singles or vinyl versions of the track produced by the Pet Shop Boys. private.rar
In most cases, a file named private.rar is a user-created folder compressed using WinRAR or similar software. "Private