if you want to scroll through replays automatically then afaik you have to move all other replays out from your replay folder and then you just open the game and it shows the replays in the menu

or then you could name them so that they're next to each other in an alphabetical order and then you cycle through them with ctrl + \ and ctrl + ] if you're using an american keyboard
or on an european keyboard i think it's whatever keys you have between p and enter together with ctrl
i'm using a scandinavian keyboard and for me it is ctrl + å and ctrl + ¨