FWIW, I registered on that forum, checked the link, and refreshed the page about 10 times experimenting. The horizontal scroll bar was there while loading, but goes away when the page is done loading, just as the javascript has kicked in and shrunken the large image. The horizontal scroll bar appeared again when I clicked the yellow toolbar to expand the image, and disappeared when I toggled it back to small. In short, it worked exactly as it seems it should. I tried my damndest to recreate the behavior Smoothie is talking about, but could not.
I am using Safari 2.0.4 on a MacBook Pro. I also have
Saft installed but I don't think that would have any effect on something like this.