Hello Vaishali,
The PMP Exam is NOT a test of your knowledge from the PMBOK Guide. Instead, the PMP exam is based on the PMP Examination Content Outline, which you can find at
www.project-management-prepcast.com/pmpoutline
. This is the document that describes what you will be asked about / tested on during the PMP exam, and the PMBOK Guide is 'merely' one of the references where you might find the correct answer. Not all topics from the outline are found in the PMBOK Guide.
Therefore The PM PrepCast is a training course that teaches you MORE than what is in the PMBOK Guide. It teaches you the knowledge you need to know according to the exam content outline. So you will find topics in the course that are not covered in the PMBOK Guide, but which we know from both the exam content outline as well as experience may be found on the exam.