Original Trailer:
Box Set: A.2

Disc: A.04

(U.K PAL version)

Depending on your system, the location may be labeled in various different ways.

The most common being:

Title: 1

Chain: 15

Angle: 1

Chapters: 1 - 8

Cell: 1

or

Title : 1

Streams: 25 - 32

Secret Artifacts:
On (I think) any of the DVDs (there might be one or two exceptions), go to the "Special Features" section, and use your controller to highlight the "Special Features" circular title. Press your Enter button. Each DVD has a different "artifact" and description. So far, there is no indication as to why they're there.