This looks like parents and chicks waking up, doing the morning ritual of preening together. In fact these are two different species. The large grey “parent” birds are Willets. The little ones are Black Turnstones. They’re not related, but they’re frequently seen keeping company. Moments later, all the turnstones flew off across the water, leaving the Willets alone. That’s just like human parenting sometimes.
The Willets have an unusual parenting pattern. Both sexes take turns sitting on the eggs but the male always takes the night shift. The female goes away about two weeks before the chicks fledge, leaving the male in charge of them.
Willets used to be on the human menu the way that the so-called Rock Cornish game hens are today. John James Audubon wrote that their eggs were tasty and the chicks “grow rapidly, become fat and juicy, and by the time they are able to fly, afford excellent food.” That’s history now; hunting the Willet is illegal.
The turnstone does not have a history as a human delicacy. They breed in northwestern Alaska and come here for the winter. The ones in the video are likely on a stopover during their northward migration. Willets can be seen here year round; check out these posts.