OK, here's the rest of the story, as a certain radio host would say.
The guy who took/collected those photos (let's call him John) put some effort into it, and wants people to come to his site. Also, John is paying someone for the internet connection for his web site, and every time someone views a photo hosted on his site John has to pay a little bit of money. It's not a lot, but it can add up.
So John has some time, effort, and money invested in his site. When you include one of his photos in a post, the photo isn't copied to our server... you're just including a "pointer" that lets browsers know where the image is on John's server. John has to pay a little bit every time someone reads your post, but he doesn't get any credit, and no one learns about his website.
Some folks are fine with that; you can link to images on their site and they don't mind at all. Others do mind, and take steps to keep it from happening.
In this case it looks like John has told his server not to show you any images from his site unless you're looking at them on his site. So, when you read chosen's post and your browser goes off to gassigns.org to fetch that photo, the gassigns.org server just says "go away."
The "polite" way to refer people to a photograph in someone else's collection is to provide a link, and maybe describe what it is they're supposed to look for, like this:
The bottom photograph on this page.
Hope this helps. This whole "showing other people's images on your own site" business has been a big, messy can of worms for, oh, about 20 years now. Some people say it's not a violation of copyright law - you haven't copied that image, after all, just included a reference to it - it's still coming from the owner's site. Other people disagree. I'm going to let smarter people (or people with more free time 
) than me debate that part, just wanted y'all to understand what happened here and John's possible motivations for not letting those photos appear in chosen's post, even when it's probably not a photo John himself took.
-Robert.-
