To get this, you must have a friend online with the game. Once you are ready to get this, you must have some saved replays (min. 10 that are not your own). You must go to the multiplayer menu and select replays.
This will take you to the replay menu. Then select share replays (or something along those lines-last option to the right). You will be placed into a lobby. Invite your friend and once your friend joins you, both of you must select ready. The host will then select 5+ replays to watch and once you hit "B", it will return you to the lobby when you can select "start" to view the replays. once you complete the 5th replay the achievement will pop. Each video, to count for completion will end and return you to the lobby where you can rate it. You don't need to rate it.
At this point, you don't need to select anything or rate the replay. the next video will start automatically. The achievement will pop for both of you once the fifth replay is completed.