He means, you would donwload a theoretical rom containing the game with its entire pre-rendered world for each level. Which would mean that given a large enough 4k screen you would be able to play a game without scrolling. i.e. the entire level would show on the screen at once and you would only move the player character around it. =) nice idea =)

edit: same thing as mentioned by ArtWomb in another comment >" This would make a cool art installation. If you can get access to one of those giant screens that you see demo'd at E3. You can visualize the entire Land of Hyrule from Lengend of Zelda. With a tiny Link navigating his way through the world ;) "