Images, videos and 3d objects which may be attached to several actions each can be stored in the media library. No need to upload the same multimedia file every time you want to use it with a new target. Media files from the GO library will be offered as an option when creating a new button.
In order to add a new media to the library, just select the media type and point to the target file. You can also decide to share it with your colleagues by activating the 'public' option.