Fantastic info CC! Useful to clarify the definitions between secondary, hidden and subliminal.
Why would they do this?
Advertisers know the powerful psychology behind the use of imagery. Every colour, number, actor, prop, etc that are used in adverts are chosen for a reason by the advertising company.
I figure with WT has a similar purpose, this is especially notable in the videos they produce - propoganda in word and image, even the choice of the actors! If you look carefully in the back ground of scenes all sorts of things show up that don't seem to have any rhyme or reason to the placement but just like movies and commercials nothing is left to chance in productions. It would be naive to believe otherwise.
WT has always peddled cult propoganda shamelessly and purposefully because they know with enough exposure the message really does get in to your brain.