You think it needs a lot of coordination to fly in sync? I only have a slow clap for you, actually everybody else join in for the clapping and without any coordination whatsoever you'll notice that we clap in sync after a just 50 seconds https://www.youtube.com/watch?v=Au5tGPPcPus
This slow clap thing is a tradition to ask for an encore/bis/repeat at concerts. So I wouldn't be so quick at stating that this is an emergent phenomenon.
But maybe this has become the tradition because when you clap for a long time it would slowly synchronize.
In the video it is quite clear a few people are seeding the synchronisation.
Just don’t clap on the 1 and 3, please. Lots of videos of musicians attempting to get the crowd to clap on the 2 and 4…but the audience has a mind of its own.
Also the changing of the point goose one guy takes over the lead falls to the back and one of the two of the V behind the main goose takes over.
And they never shut up, plus they are so loud. They're talking about something.