O replayach i spectator mode pisano juz od samego poczatku w FAQ
Cytuj:
Q: Will the replay system allow me to move freely backwards and forwards in time rather than having to watch a whole replay? (by Luciando)
A: You’ll be able to jump around to any point in the replay, add bookmarks for easy referencing, view detailed stats and graphs while the game is going, and watch through a specific player’s view (with regards to their camera movement). You’ll also be able to watch replays with friends if you want to review a game or learn from your mistakes. To aid videomakers, the replay system will have flexible camera angle and speed controls. There will also be a bunch of commentating and editing features you can add to your replays.
Cytuj:
Q: Can you spectate an already ongoing DotA 2 game? (by Valo)
A: A lot of the game will be built around spectating and shoutcasting support. You will be able to join most ongoing games (unless the players marked it as private) and just watch them. You can join a game your friend is in, see what your favorite clan is doing, or simply pick a skill level and a hero you like and it will find you one to watch. We also have a system in place that automatically distributes the load to multiple servers so that the game itself won’t be affected by users joining to spectate. Our distribution network will allow us to support any number of users that want to watch, by dynamically assigning more servers to the task. There will also be special tags and search options to help you find live or old shoutcasted games. Shoutcasters will be able to operate as directors, so anyone watching will have his camera looking at the same things the shoutcaster is viewing. There is also an optional anti-cheat mechanism built in so that the game you are spectating can be time delayed by any amount of time to reduce potential abuse.
Btw. herosow jest caly czas 35? czy juz wiecej zaimplementowali?