Are you aware of the SC2 interface/render hooking system[1]
by Matthew Fisher? I've not actually had time to play with it, but I believe it uses a software-emulated display buffer, and then parses the raw directx drawing primitive stream to determine what is happening.
I'm not sure if it supports replays, or how much effort that would be to add, but if it can, you could extract huge amounts of metadata like build timings/orderings and whatnot.
[Edit: and of course, if you can render to a virtual screen, maybe there could be some way to run headless or multi-instance on a single box]
If you can get the suitable video player controls, it'd be fun to integrate it with an interactive timeline something like SMILE[2] to show significant events throughout the game (first discovery, first unit death, 'interesting' (say, involving more than X units or Y diversity of units)
[1] http://graphics.stanford.edu/~mdfisher/GameAIs.html
[2] http://www.simile-widgets.org/timeline/