Yeah, you had to add the command: -allowIncompatibleReplays
@AlleyCat, to do this:
Select COH2 in your library -> right click -> properties -> set starting options (or something like that, my Steam is in Italian) -> paste "-allowIncompatibleReplays"
Please note that while you will be able to watch old replays, they will not really work if any unit data has been changed on a more recent patch. For a better explaination there is a good Reddit discussion you can find here:
https://www.reddit.com/r/CompanyOfHeroes/comments/2ouee3/how_to_watch_old_replays/
![Honor icon](/images/replay/honor_icon.png)