Here's a short summary of the Hacker News post: A Hacker News post links to a YouTube video about the mathematics of juggling. One commenter pointed to a video and wiki about "negative siteswaps" after watching to ~43 minutes of the juggling math video. Another commenter, a juggler/magician, enjoyed the talk and highlighted the difference in perceived difficulty versus actual difficulty. They mentioned the "shower" pattern as being harder than the cascade, despite both using three balls, and the "claw" pattern's added challenge. The commenter also noted the importance of choosing tricks that are easy to learn but visually impressive for audiences, while expressing frustration with learning faro shuffles. The bottom of the page is a YC advertisement and site information.