[thomasfedb]

I’ve heard (can’t tell for sure from the photos I’ve seen) that they were “dressing the yards” at the time - which is when the crew stands on top of the yards (the horizontal spars) side by side. It’s done for ceremonial or celebratory reasons, not for work.

[jabl]

You're right. As can be clearly seen in the snippets shown in https://www.youtube.com/watch?v=gIlRiauatEo