As Netflix explains:
Each preview is about 30 seconds long and presented in a vertical format, so you can watch them without turning your phone. The previews are shown like a slideshow, so if you see something you like, you can tap play or add to your list. If not, you can swipe or tap the screen to advance to the next preview.
At launch, mobile video previews in the Netflix app are available for “many hundreds of titles,” according to Netflix’s Todd Yellin and include both originals and licensed shows.
Netflix mobile video previews for the streaming service were first introduced through the Netflix TV interface. It’s great to see this feature extended to the iOS platform with Android coming soon.