A Vine Trailer is a small preview that is played for members who have not yet purchased its content. The trailer will also be generated in a GIF that will play when members hover over the thumbnail of the vid. 

You can generate a 9 second preview from the vid or upload a custom edited trailer that can be up to 30 seconds long. 

When editing the details of the vid (click <Start> after uploading, or click <Edit> on your profile vid or in the  Content Manager  after posting) look for the section titled "Preview", click in <Edit advance> and you will be given the following options: 
Create from the vid
Use this option to select a 9 second clip of the vid you are uploading as a preview. When using this option, the preview cannot include the first or last 9 seconds of the vid. After making your selection, a progress bar will appear to let you know when the progress has been generated. 

Upload
  Selecting the "Upload" option will open a window to select a vid file. The length of the file should be between 9 and 30 seconds and no more than 50 Mb. After making your selection, a progress bar will appear to notify you once the file has fully loaded. 

Once a trailer has been generated or loaded, you will have new options available in the "Preview Options" drop-down menu.
The <View current trailer> option allows you to review your trailer to make sure it is exactly the way you want it, and the <Download trailer> option allows you to download the trailer, which can be great for promotional use! 

Looking to add or generate a thumbnail for the vid? Click here to find out how.