It also doesn't actually work correctly - if you scroll too quickly it doesn't load more content. Possibly just a CSS issue on the example because the last row is not visible when scrolled to the bottom of the page due to the footer and its large margin.
Infinite scroll is not a good tool for his use-case. Users will filter and then try to Cmd-F. They will get annoyed if you can’t search. It’s just bad UX. You can use infinite scroll for things like Twitter feed. Product search is just a different kind of UI.