Well, I can give you the basics of the tutorial, not sure where it’s hosted now.
You basically need a pre-comp of a few people cheering/dancing/waving arms/whatever, then use this pre-comp as a custom particle for a Box emitter with high values for x and z dimensions, and a very low value for the y dimension (alternatively you can use a solid layer emitter). Set the emitter to have 0 velocity, emit the particles with a random starting frame + loop. Increase the particle life span and size as you need it. Under ‘Options…’ set the pre-run to 100%.
These are the basics… you can work out the details to your liking.
Darby Edelen
Designer
Left Coast Digital
Santa Cruz, CA