The Library of Congress has prepared a brief video to convey the need for web archiving and to describe web archiving efforts at LC. This video provides a good introduction to the collection, access and technological challenges faced by web archivists.  Note that the archiving protocol described, particularly the rights management activity, is specific to the Library of Congress. 

Library of Congress Web Archiving Video

Library of Congress Web Archiving Video

Video link: http://www.digitalpreservation.gov/videos/webarch09/index.html
Running time: 3:10