Let's try to help you - here's a revised version of what I said:

1. The exact relationship between the number used to represent a throw is complicated.

2. When you use the relationship, you end up predicting that some throws have to go backwards in time.

3. SiteSwap predicts the existence of juggling tricks that use these "Time-Traveling" throws.

4. The juggling tricks can, in fact be done.

5. We interpret a ball going backwards in time as an anti-ball going forwards in time.

So, which bit don't you get? Ask, and I shall expand.