The first image exceeded the 2.5 mb image size limit of bitcointalk that's why it doesn't show.
Ok, thank you for the lesson. I was always wondering seeing all those images on the topics showing proxy issue. So, it's for this size reason or there are many other things are involved?
No, that's not always the issue.
AFAIK it might be as well because of a broken link due to the image hosting deleting the image or on having the link without the .jpg extension.
At least with my experience. With the one image being 2.8 and setting it aside. It seems Theymos wont allow images from anything other than imgur and maybe a few other "name branded" places.