Which bird is it?

Thick-billed Murre and Common Murre
Uria lomvia and Uria aalge

The breeding distributions of the northern Thick-billed Murre and the more temperate Common Murre overlap broadly in this region. The two closely related species are about equally abundant in the Aleutian Islands, however the Thick-billed predominates in the Pribilof Islands.

Both species usually nest on the ledges of steep rock cliffs. The Thick-billed tends to occupy relatively narrow ledges, whereas the Common uses wider ones and often occupies broad flat platforms above more vertical surfaces. Murres build no nest, typically laying their single egg directly on the rock ledge.

Both species can be seen in the video, however, there is only one Common Murre, right in the center of the Thick-billed Murres in the final image.