Please don't mess with my ability to scroll through content. Additionally, having content in between the nav breaks is infuriating, and my scroll bar is gone.
In other cases I’m also disturbed by the broken scrolling but in this case my only complaint is the space bar not working. This is a slideshow, but it feels like scrolling because it goes vertically and the scroll bar works. I’m pretty sure if the scroll bar were completely disabled and there was a [next] button with a different transition you wouldn’t complain because you wouldn’t think of it as broken scrolling, but just as another slideshow.
So, my suggestion to the author: make it slide horizontally.