But that could be changing. Those in the U.K.visiting the "featured" section of the App Store are able to view a video trailer for the game Clumsy Ninja. The video lasts about 1 minute in length. The game is the Editor's Choice of the week in the region and could be featured in the U.S. App Store and other international versions of the store on Friday.
We need to point out that the video only appears on the "featured" section of the App Store and does not show up on Clumsy Ninja's regular App Store page. We also don't know if this is the start of a new feature that will be available for other apps or just for this one game. Surely iOS users would love to have the same ability that Android users have to see an app in action before making a purchase.
source: MacStories via Engadget