Originally Posted by мusịĸ
>An offline method
All the information is processed from the server (unlike war3 whereas it's processed from the host/clients) that's why maphacks are pretty much impossible in dota2 and saving replays from the clientside is not possible because information outside the fog of war is not sent to you. This is why you have to download each replay from the server and can't process t from your pc.
And believe me, dota2 replays are so large if they auto save to your hdd every game you'll run out of space very quickly.