And what that means is that your trailer should, within its opening seconds, make a curious statement, ask a provocative question, or show an intriguing image that will immediately hook the viewer."Your book trailer must instantly create a curious desire in the viewers mind."
Opening with your setting is an excellent hook that leads to more interesting happenings (fill in your events here) which will unfold as the seconds tick to hopefully a bigger, even more interesting question or an open-ended answer. Take your pick. Point is, you must hook and reel in the reader to a point when their curiosity has peaked. By the end of your presentation, your reader must be so intrigued, so curious, and so eager to find out not only more about your story, but its fantastic ending as well.
Your story does have an amazing ending doesn't it? Sure it does. And if it doesn't, you can now look to its opening where you'll find the answers to that amazing ending you've been after for so long. An ending you'll just hint to or suggest in your trailer, but remember not to give away key parts of your story.
Maintaining a sense of mystery and suspense are key elements to good storytelling and just as important to your marketing concepts. So the next time you're stuck on how to open your book trailer or what kind of device to use in a banner or promotion. Think of your reader's most salient desires within the context of your story narrative and...let it fly.