A lot of information and stracture, that can help you build a good video for you app page:

  1. Choosing a video type (Teaser, In-Game or Trailaer)
  2. Idea and script
  3. Source materials
  4. Storyboard
  5. Voiceover
  6. Animation
  7. Music and audio
  8. Localization

Full article at:
http://www.gamedev.net/page/resources/_/business/production-and-management/how-to-make-videos-for-games-r3683