You are looking at the prototype that was in 4.7. DFGI (4.8) does NOT sample SceneColor. Surfels (oriented disks) are placed all over meshes capturing their position and diffuse color. Those are then lit with shadowing to compute how much light they should bounce. Then the scene is lit with the surfels as if they are point lights - Virtual Point Lights. Distance field occlusion is used to shadow these VPLs.
Even with 4.8, I don’t have emissive hooked up yet. It should work well for a single object like that, but not for small bright emissive spots due to the surfel disks being fairly sparse.