That is a great video. They look great, eating and drinking too. I don't know for fact but wonder if that goop could have even be left over from hatching @WVduckchick or @Ravynscroft will have to comment on that. But looks to be clearing up. Put enough ND into their water to make it look like weak tea. Unless you have directions on the bottle I have a large bottle and bought a small one with a dropper I put 2 dropper squirts into a gallon bucket for mine.