In other news, the Dota 2 blog has posted quite a bit of info on the game's spectator system. While it will obviously allow players to view match replays, it sounds like it includes a lot of customizable functionality as well. Players will be able to filter replays by certain characters, certain players (friends, pros, etc) and even certain skill levels.
For example, if you're trying to learn how to use a certain character, you could search for a replay of a high level player who uses said character. Viewers can even see a replay from a particular player's perspective, including "the player's mouse cursor and input, their camera work, their HUD, their interaction with UI elements, and so on." It sounds like spectator mode could be a great resource for new players and anyone looking to improve their game.