Currently, the option to download a video or an image directly from a published site is not available yet, but another option is to use a third party, or Zoomforth's native, file hosting service.
For more information regarding Zoomforth's public file hosting, please check this article.
Once the asset has been hosted online, get the website address to access it, and create a text, or appropriate media tile. You can then create, either, one of the following:
Hypertext in a text tile, or
External link to the hosted file
The site visitor should be able to click on the hypertext or asset tile to download the asset through the file hosting service.