To be able to use My Movies for iPhone, you are required to have a user account on our service. The overall reason for the requirement of a user account is that My Movies for iPhone although functioning as a standalone product is also part of a product suite, where your movie collection can be shared between multiple solutions.
To be able to give you easy access to the same movie collection both from multiple clients and other products in our suite, your movie collection is stored both on your device or devices, as well as on our online servers as references to the title profiles on our service. You can read more about the benefits of this in the section "Data Storage Explained".
This approch does not mean that you are required to be always online with your phone to use the software - the data is also stored locally on the device, and operates well, even when you are not online.
This shared collection means that you at any time can install My Movies software suite for Windows, and be able to manage your collection from it, even though you added your titles from a mobile device. Users who are alredy using the software suite for Windows can simply synchronize their collection with the servers, and then use the same collection on the mobile devices.
Last, you can though the software suite for Windows create an online collection, giving you a website to share with your family and friends for them to see your movie collection online. The option to create an online collection will later be added to the mobile device software as well.
The overall benefit of having a user account, and having your movie collection stored for this account, rather than on individual devices only is that you will have access to the same unified movie collection from multiple devices and products at the same time, without ever having to consider data imports, exports or backups.