i just feel sad for all the new people/old timers wanting to play/get back in wow.. they all gonna spend days and days downloading all the patches, and extensions and if unlucky, the might have to restart the whole process lol..before they can actually play.. hahaha.. what a turn off!!!!!!! damnit blizzard!!!
imagine in 5 years, how many expensions wouldve came out...
and how the hell would new ppl would even get to the top..they gotta spend like crazie hours...

Blizzard Background Downloader has three phases for three 'types' of patches.

Red phase - Downloading vital stuff. Can't start up WoW at all.
Yellow phase - Downloading important stuff. Can start up WoW, but MAY have performance issues during play.
Green phase - Downloading trivial/unimportant stuff. Can start up and play WoW, stuff will continue downloading in the background.