In the not so distant future, visualizing and "walking through" the past -- ala the movie Deja Vu (but minus the wormholes) -- will become a reality. It was the lack of even a rudimentary version of this that made the Reddit sleuthing so hopeless, with most media having zero context, location, or even time taken, that metadata not available.

But imagine photo synth/streetview with a time slider: Thousands of pictures and overlaid videos time synchronized and placed into a scene. Such a tool could be incredible for such investigations.