Scrolling is a separate matter. I didn't even bother to scroll the first time. I just pressed the next/previous buttons on the slide navigation bar.

In the scrolling case, I still don't see how it's "overriding the browser buttons", but rather having a JavaScript that advances to the next page on scroll.

In the scrolling scenario, my actual back and forward browser buttons behaved as expected — just for the pages (slides) I visited. No more, no less.