Make a download folder in the replay folder named "Downloaded replays". Then, when you click the attachment you wanna look at. After that it says "Open" or "save" or "cancel". Click "save", and browse until you find the "Downloaded replays" folder and thyen save the replay. After that, you click on the "Open folder" button and voila! You can watch the replays without bigger concern. And when the folder starts to clutter up, then you just delete the replays and start saving them again.

I hope this is a working solution for your replay problem. I've tested it and it works.