IDK actually.
From the Help section:
Registration is Free! By creating an account and signing in:
    Get 10 GB of free space
    Upload files up to 2 GB
    Unlimited Downloads and Transfer
    Profile to publish and share your files and folders ( example )
    Follow friends to see what they are sharing
    Use Dashboard to manage your files and folders
    Search and discover public folders
    Many additional features
Minus has desktop, mobile and browser tools on Windows, Mac, Ubuntu, iPhone/iPad/iOS Devices, Android devices and Google Chrome and Firefox extensions. 
You can use Minus to:
    Create an online portfolio of your work with your Minus profile
    Share photos and videos from your recent trip
    Publish your work whether it's an ebook, music, photos and more
    Brainstorm and share your next killer project
    Collaborate and share design mockups, code snippets and beta apps
    Backup your important files, documents and access or share it later
    Share lecture notes with your class
    Share anywhere via the browser, desktop and mobile