An improved hierarchical user interface for a handheld media player is disclosed, which classifies media assets that an on-line merchandiser intends to sell to the user as hidden files. The files are invisible to a user without a user's intended and persistent interaction with a user input device of the player. The media assets that an on-line merchandiser intends to sell to the user are stored in the unused storage capacity of the player and are organized in a single structure as those media assets owned by the user. A method includes a means that a user actuates a user input device until the hidden files are displayed. Furthermore, a method is disclosed to utilize a file storage system of a portable media player more effectively and efficiently. The unused storage capacity is then used by the on-line merchandiser to store media assets, which have not been purchased by the user at the moment when they are received by the media player. The capacity occupied by the media assets from the merchandiser is adjusted dynamically based upon the required capacity by the user at a specific time. The media assets stored are managed based on their assigned priorities.