[ame="http://www.youtube.com/watch?v=g2zDpl-OQc8"]Sections of a Pork Butt - Money Muscles & Tubes Pork Shoulder - HowToBBQRight.com - YouTube[/ame]
You can watch all the videos you want but as said above you need to get your hands in there and seperate the muscles apart to learn them.
This will help tremendiously when pulling pork for catering as well.