Here’s a mind expanding video explaining siteswap. Interesting to see someone explain the mathematics of juggling movements, while someone else is doing it, when what they’re doing looks totally impossible.
That whole Gandini Juggling vimeo account is a goldmine, they’ve put a DVD’s worth of material up for free. I really have no hope of learning any of it though 
thanks 
i’m very much not a video person so it’s very hard to watch a 50min one for me, but I will send this to my mom that I somehow really got into juggling math (with this book that I lovingly recommend: The Mathematics of Juggling | Burkard Polster | Springer)
This is awesome
I stumbled on a video demonstrating ‘negative siteswaps’, where balls are thrown back in time. It’s done with ‘antiballs’, which cancels out when it meets a normal ball…
" When a ball changes from going backwards to going forwards in time, it looks like a ball and an antiball appear out of nowhere and are thrown as a multiplex. Both of these are actually the same ball; one is the ball going forwards in time, and the other is the ball going backwards in time. The antiball comes from the future, turns into a ball, and goes back into the future, so it doesn’t exist before that time as a ball or as an antiball. When a ball changes from going forwards to going backwards in time, it looks like a ball and an antiball come together in a squeeze catch and disappear. The ball comes from the past, turns into an antiball, and goes back into the past, so it doesn’t exist after that time as a ball or as an antiball."
As well as great performances there’s a lovely discussion in here about differences / correspondences between jugging and music improv:
A nice summary of siteswap from a mathematician: Juggling Talk Summary