Ah, that answers that, Beanie. When you pasted the URL and looked at it that way, you put the image into your cache. When you backed up to the thread, the image was displayed from your cache rather than from the link. By going out to another forum and then back, you reloaded the page and tried to hit the link again and got the red X.
Now I've heard of slow but this is getting ridiculous. It is now 10:31 AM and this reply still doesn't show up as the last post to this thread!! As you can see, I posted this reply at 10:09 AM.