The app also installed very quick without much hassle. Once installed, don't worry about the register ext thing. It is compatible with most ext by default. Only register an ext if the ext not working on the first time. The application can be uninstalled using the Uninstall option available on main interface. It will unregister all the file extensions, and then remove the application.
It is a free application for Windows 7, Windows Vista and Windows XP from AddictiveTips.
The main interface. It's simple and actually you have to worry about registering the files extension.
Just select and drag into other files.
This dialog box will appear to name the folder. Then all the selected files will be in the folder.