Curiously Weak DRM (in University Press-Hosted Companion Websites)

I was just scouting out a new academic book of interest to me using Google Books. I was able to browse chapters, study the table of contents etc. The book is published by one of the largest of the university presses. It can also be browsed in Amazon.com. On a subject where audio and video is relevant, the book has a companion website hosted by the press. Information on this companion website is available in the front mater for the book. Looking at this page in the Google Books representation, I saw the URL followed by:

To accompany “TITLE OF PRINT BOOK BY MAJOR UNIVERSITY PRESS HERE”, we have created a password-protected website where readers can access the recordings linked to the chapters.”

Access with username XXXXX# and password XXXX####.

The user name and password are presented as fixed text in the book and they are visible to everyone via the Google Books version.

What factors could account for the imposition of DRM (Digital Rights Management) in such a weak, permanently affixed, and circumventable form? Did they not put the media on a straight open platform because they promised the rights holders that it would only be available to purchasers of the book? (Including library users.) Are there actual advantages to doing things this way? How reliable a preservation framework is implied by the strategy used by this (very large) university press? Does anyone expect this website to exist and work (via this username and password) ten years from now?  Is this standard operating procedure and I have just not noticed it yet?