They’re actually a new 3D process that uses clear lenses. The lenses make certain colors appear to stand off the page. They work with any printed matter, especially if it has clear, defined colors (i.e. comic books are great with these). They make red appear to stand out, so they’re especially suited to VB.
The Nintendo Power 3D glasses came in a small envelope, which said “FOR YOUR EYES ONLY” on the front and “OPEN HERE… AND MAKE THE PAGES OF NINTENDO POWER ENTER A NEW DIMENSION” on the backside.