As no giveaway DVD with the consolidated ppt/pdf materials from BlackHat’s US 2014 briefings was shared during the start (nor the end of the event), you will have to download the presentations by yourself one by one, to speed up a bit the process you may use the below bashfu:

for i in wget https://www.blackhat.com/us-14/archives.html && grep "../docs" archives.html | sed 's/\.\.//g' |awk -F "\"" '{print "http://www.blackhat.com"$4}'; do wget $i;done

by