Seems like there are several ways to use PMBOK and Prepcast videos together.
Options 1. Read PMBOK cover to cover while making notes (I use onenote). Then view all prepcast videos after. Supplement the notes with new learnings or for emphasis.
Option 2. Read a PMBOK chapter and view corresponding prepcast videos for same chapter right after, then move on to next knowledge area.
Option 3. View prepcast videos for a certain chapter, then read corresponding PMBOK chapter right after before moving on to next Knowledge area
I followed Option1 and it worked for me. I guess to each his own.
YES i asked if i would be allowed, and they said i can bring my own (foam) earplugs as long as there are NO CORDS/strings. It was also mentioned the printed instructions at the prometric site when i signed in at the day of test. Best to call your center/site and inquire to be sure. I found it helps to condition my ears to use them while studying so it wouldnt be any different when i wrote my test.
you should be able to find the download button on the video page of prepcast. (three tiny dots at the bottom right corner of the video screen). Download each video manually.
Hope this answers your questions. GOOD LUCK and Blessing be upon you.