We’re going to be patching StarCraft II soon, and the changes in patch 2.0.10 are significant enough that replays from previous versions are incompatible with StarCraft II 2.0.10 and must be loaded in earlier versions of the game. But this doesn't mean you can't watch your old replays!
StarCraft II has always automatically loaded replays in the appropriate version of the game behind the scenes, so you can continue to watch your old replays just like you always have. Something you may not know is: when StarCraft II loads a replay in an older version of the game, it has to disconnect from Battle.net. This means that some of the new, advanced replay features that were added in Heart of the Swarm aren’t available when watching replays that were created in 2.0.9 and earlier.
Simply put, after patch 2.0.10, you won't be able to watch old replays with your friends, and you won't be able to recover multiplayer games from replays created in 2.0.9 and earlier. This was also the case when Heart of the Swarm was released -- watching replays with others and recovering games only worked with replays created in 2.0.4 and later.
In patch 2.0.10, we’re continuing to make improvements to the replay system based on community feedback. You can now jump ahead to any time in the replay. Prior to 2.0.10, you could seek backward in a replay, but you could only jump forward to the latest timestamp you'd already reached when watching the replay.
Now you can jump ahead, and the replay will seek ahead as fast as it can and automatically resume playing when it reaches that time. This works when watching a replay by yourself or with others, so it's now easier to jump ahead to a key point in a game with your friends and Take Command so you can re-fight the battle trying different strategies.
At the time of this posting, patch 2.0.10 is coming soon, and we intend this to be a heads up for those of you who are currently working with replays in various ways. We’ll have full patch notes for you in the days to come, and we’d very much like to hear from you on this in our User Interface forum.