Why is the pilot in this video retracting the spoilers so shortly after landing? I watched this video (link with time) and wondered why the pilot has retracted the spoilers so shortly after landing.

Because the runway is wet and it looks like the plane is still quite fast even in slow motion. Wouldn't it be better to have more braking grip?
The pilot doesn't retract the spoilers until the airplane has slowed down considerably, at the speed it's traveling at that point the spoilers would be adding no benefits so there's no point keeping them deployed.