I always wondered: If a pensieve is a memory, surely only the things one sees can be remembered. The visitor should only be able to see things from the view of the original baal-hazikoron! How Harry – every time he visits – see things from different angles? See other details?
If a memory is a magical concept that can be altered, removed, planted and stored, then it is not confined to that which is directly in the subjects sight-line, rather an imprint of the subjects perception in that given time. It would seem the one visiting the memory cannot perceive more than the subject, for example a conversation the subject was too far away to hear or a room he never entered.
I wonder what would happen if he tried? The memory would probably break down in some fashion.