The cynic in me feels that much of what they may be determining is from muscle artifact...i've been looking through some (plain old clinical/medical 32 electrode) EEG data and even that has a lot of artifact. Although I suppose it's some behavioral correlation - the more stressed out you are the more you clench your muscles, I suppose.

At the very least if they've figured out how to get clean EEG w/o having to use smelly EEG conductive goop, props to them!