The copyright for the screencaps used on this guide is most likely owned by the company or corporations that produced it -- NBC and Universal Home Video. Their use qualifies as Fair Use of the material under United States copyright law under the following auspices:
Their use here is entirely encyclopedic;
Their use in no way limits or hinders the copyright owners' rights distribute the television show in any way;
The image is being used in an informative way and should not detract from the original work.
Warning: The Office (US) guide may contain spoilers