It kind of seems your overflow is not draining/matching your pump flow? Also maybe think about feeding your refugium from your drain and not how pump is plumbed. Send 75% thru socks and 25% thru refugium.....just numbers can be different. This way you feed your refugium non skimmed water. The water height at your pump area should be 1" below teeth or your set up isn't plumbed how you designed/build your sump
Top off water only matters when your sump is running right, how much evaporation are you losing a day doesn't seem like a lot with that size system?
I know your sump isn't running right NOW but when you get it going hope it moves faster than your video because too slow of flow has limited gas exchange and lower oxygen levels as you know