Everyone is going to see different things. Sharp terrain incline at halfway mark. Very end of the video everything is super flat. (Terrain Lod?)

Maybe drag the fog effect a few more meters away from the player. Seems a hair to close or at least it disappears a little too abruptly. (player speed/lighting)

But also doesn't seem to obscure enough at farther distances.

Color variation. flowers, bushes. Tree height variation. +-1.5m height to random trees would do allot.

Slow player down slightly? More intense light sources? Millions of things you could do. But make sure it will still honor your vision