Imagine a future where everything that happens in public spaces, and perhaps much in private spaces as well, is routinely recorded, saved and searchable. In that future, the man of thirty gets to watch himself at fifteen on his first date, judge how reasonable or otherwise the quarrel that ended a friendship at eighteen was, see how his parents treated him and he them, with perhaps useful lessons for bringing up his own children. At fifty he gets to look back at what he was doing when he was thirty, recognizing faults or errors invisible to him at the time.
It works for shorter time periods too. After the political argument or lovers quarrel in which my behavior was, as I saw it, entirely reasonable and the fault all on the other side, I get to rerun an outside view—and perhaps see how my voice tones, gestures, facial expressions conveyed a very different message than I chose to remember.
Google's usenet archive already provides a pale ghost of such an opportunity, limited to a string of text messages. The future may expand that to full motion, living color, perhaps even 3D.