The long pull on an ecig that you see in the videos is by design. With a cigarette, you pull hard to get the coal hot. That produces more smoke. With an ecig, when you press the button the coil is the same temperature until you pull. Then, you draw cold air across it and the temp goes down. Pulling gently for a longer time produces more vapor since you are limiting the amount of air drawn across the coil.
4 to 5 seconds slow pull is pretty much what most vapers fall into. Drawing into the lungs is popular, but you get more absorption through the mucous membranes in your mouth, throat, and sinuses than you do in the lungs themselves. Seems that tobacco particles of combustion that made up smoke are actually microscopic ash particles coated in nicotine. You draw those into the lungs and they penetrate into the air sacs. The mist from an ecig tends to coat the lining of the lungs and most doesn't make it into the alveoli like ash particles of smoke did. My personal thoughts are that if you hold it in long enough most of it settles to the lining in the lung and that's why you blow out less vapor than if you inhale and quickly exhale. There's not enough clinical information on how the process works to suit me.
