This tutorial explains how to add media files to your application in addition to simply attaching / uploading them to your application.
Here are a few pointers to help you link media files from the services DreamApply supports:
1. Find out here How to add a Vimeo video
2. Find out here How to add a SoundCloud track
3. Find out here How to add a YouTube video
4. Find out here How to add a Dropbox media file
These tutorials represent a general approach and are subject to change in case the software provider updates its processes.