@ultimafantasyx9:
IIRC, you put the replays in the /savegame directory, then can load them up in game.
Replays in most games I believe are laid out just as a series of actions. Each command a player issued is saved, attacking, moving, making unit, using a skill etc. So the game is played back identically to how it originally was. This allows for small recording file size, but causes incompatabilities between versions.
On the topic of fast forwarding, I think Age2 had chapters that you can save, to fast forward recordings to a specific point, but you had to save them while playing, and I never saw them used.
I don't mind optional allowing of replays, but I typically save all of my own games from Age2 and WC3.
Playing: Poker. Yay.
Retired: Age of Empires 3, Warcraft 3, Guild Wars, Dark Age of Camelot, Age of Empires 2.