The idea is to expose all the stationary elements of the scene in a series of shots. The number of shots and time between them will depend on how crowded the scene is and how quickly people move about.
I think the possibilities are very cool with this. Not sure EXACTLY what you do about those moving clouds and changing lighting. But with Photoshop, I truly think anything is possible. Might take some work, in fact A LOT of work. But images can be sold for stock photos and so the perfect shot becomes the perfect moneymaker.