The files that are stored inside the archive (it's also called "storage") are served directly by web server from the archive, without unpacking them to temporary directory. Due to various techniques performance is not affected.
Size of the archive can exceed 4GB. I.e. you can use it even for sites that take entire double-layer DVD.
Partial download of static files that are served from the archive is perfectly supported. This means video players will be able to play video and seek to any position inside the movie. This also means that huge PDF files will open instantly and will be loaded in the background by the PDF plugin.
Format of the archive from which files are served is proprietary, so it complicates stealing your intellectual property as much as possible.
It's not possible to serve server-side scripts from the archive (e.g. .php or .jsp files). In order to protect them, it's recommended to use third-party protection tools (e.g. ZendOptimizer or IonCube Encoder for PHP files).
To enable serving files from the archive, just select 'Yes' for Store static files inside protected storage in the Project ⇒ Site Settings ⇒ General ⇒ Main and list extensions of files you need to put to archive in the textarea.