When adding inputs or operators that use external media files, Composer uses the original file path. This means that the media files are kept at the location from where they were imported.
Normally, this is not an issue, but it might be difficult to keep track of all file locations and references when copying a setup from one instance to another.

To simplify, this Composer supports a couple of useful functions.

Consolidate Media

The Consolidated Media function will copy all images & video clips used in the project to the Media directory found in the application root folder. All media references in the project will be updated to match the new file locations.
To consolidate media, use the application file menu and select Media/Consolidate...

Backup media

The backup media function will copy the images & video clips used in the project to a folder labeled hostname and backup the folder to the path specified in settings (backup directory).
To backup media, use the application file menu and select Media/Backup...

The Media Folder and relative paths

The Media folder is located in the application root directory and contains two subfolders: Images and Videos. As mentioned above the Consolidate Media will copy all images and movie clips into the two folders and update all references. Files stored in the Media Folder will be references with relative paths. Example: Images/car.jpg or Videos/intro.mp4

Relative paths are helpful when moving projects from one server to another - if a setup is using relative paths and the setup is copied to a different server where the Media path is different - but contains the same files, the setup will work. There is no need to change the file paths even if the media folder locations are different between systems.

Composer also has a number of media search functions that can automatically search for missing media.