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