Successful entertainment, to me, is defined as emotionally engaging audiences so that they're willing to buy a ticket, or dispose of some of their free time.
For me, the term "entertain" has an emotional element and a training element. (I'm sure this is NOT the word's etymology, but humor me.) Successful entertainment always emotionally engages your audience, AND it passes onto them some true moral message usually hidden in the subtext. (For the girl on the right that truth is "Never, ever believe your mom when she says, 'Trust me, you'll love it.'")
So, we have something that is emotional (E) and we have a training element (TRAIN). That gives us E-TRAIN. Also there is the idea that both the emotional and the training enter into the person's consciousness and become INGRAINED (which rhymes with ENTER-TAIN-ED -- like I said, humor me). The key word there is ENTER.
Successful entertainment, therefore, ENTERS into a person EMOTIONALLY and TRAINS them about something true. First ENTERTAIN as you EMOTIONALLY TRAIN.
Okay, Okay, so TRAIN and TAIN are not the same. Let me s t r e t c h it for ya. TAIN rhymes with STAIN, and good entertainment leaves behind a stain.... no, no, you potty head... a stain in your brain—a memory. (Geez! I can't take you anywhere.) Another way to understand this is that ENTER-TAIN is a lot like INNER-TRAIN. That is, something is "entertaining" because it has the ability to train our memories. The reverse is also true: if we want to train our memories there must be some emotional involvement, some entertainment. Memories do not "stick" without adrenalin burning some synapses together in our brain.
The long of this short post is that successful communication has three components. It must ENTERTAIN, and for it to do that it must be MORALLY TRUE (at a psychological, spiritual, or subliminal level), and it must EMOTIONALLY ENGAGE (it must be be a visceral simulation of life).
That is what stories do better than a thrill ride at an amusement park, and what stories do almost as good as real life experiences (life's best teacher), but with out the physical danger.
(And you can believe the little girl above would feel a lot safer at the movies. Real life does have its drawbacks, especially when your mother is C R A Z Y!)