A memory storing AV data for playing back encrypted video on a playback device is provided. The AV data includes a system stream file including encrypted video information, and a management information file. The system stream file includes a first segment in which is repeated a first data unit that can be individually decrypted using a first decryption key, and has a second data unit of the same data size as the first data unit but cannot be decrypted by the first decryption key. The system stream file also includes a second segment which can all be decrypted using a second decryption key that the playback device has in common with another playback device. The management information file has a time map in which are correlated I-picture serving as random access point, and a presentation clock time of the I-picture. The I-picture is multiplexed in the second segment.

In a playback method of a playback device that plays a system stream file including encrypted video information, the system stream file includes a first segment in which is repeated a first data unit that can be decrypted using a first decryption key that the playback device has and a second data unit of the same data size as the first data unit but cannot be decrypted by the first decryption key, and a second segment which can all be decrypted using a second decryption key that differs from the first decryption key. The playback method reads the system stream file, and performs conversion processing to convert the system stream file that has been read out into a post-conversion system stream, in which the second data unit in the first segment in the system stream file that has been read out is replaced with a plurality of continuous invalid packets, and outs the post-conversion system stream.

An article of manufacture includes a machine-readable medium that stores a multimedia content file in a first format and multiple program sets. Each program set is a version of software that, when executed by a respective electronic system, produces the multimedia content file in a second format for use in the respective electronic system. A first program set is compatible with a first operating system executed by a first electronic system and a second program set is compatible with a second operating system executed by a second electronic system. The second operating system is distinct from the first operating system.