Personally I have found the Primo's Truth Series very helpful in hearing the elk "language" in various situations. Elk hunting, or should I say calling in general, is about the set up and knowing the tone or excitement in which one places into his calling sequence. You will learn when to turn it "on" or "off", when to bugle over a bull and when not too. One thing is most people watch videos for the shot or harvest. I personally like to watch the non-vocal language or body language..what is he looking at ? At what extent will he give up the search ? What is he listening for ? Last year I ran the camera and below is a clip of the bull we shot. We worked this bull for about a hour, the calling prior to the footage was practically non-stop. Finally by turning it off, this bull could take no more. What I notice from the footage, as you will, the bull looks over every little "hiding" spot looking for those elk. We were about 20 yards from the crest of the hill, which the bull had to walk past us to check the last spot. Enjoy and good luck on your quest.
http://s126.photobucket.com/albums/p113/rob1dr/?action=view&current=ElkClip.flv
I personally read alot of books, but one that stands out (as I read it on my flights out west annually) is Elk Tactics by Don Laubach. Here is the link below.
http://www.amazon.com/Elk-Tactics-Don-Laubach/dp/156044682X