There no doubt a good product video will help you sell. Where possible its a great idea to supplement your products images and description with Videos.
This article shows you how to add a product video to your product via the Storefront Admin.
FOR VIDEOS HOSTED ON VIMEO
Important to note you need to grab the embed code from Vimeo, not just the video URL!
Firstly go to the Vimeo video in your browser, once there check this screencast for more info
Bascially you need to change the width to 745px, deselect a few checkboxes to now show info over the top, then copy the embed code from Vimeo, then jump into Storefront Admin and paste the code into the video field.
Be sure to save and preview...