As I explained in this answer, all the links to images that were not uploaded via the "add image" button are broken. (EDIT: See also this announcement by Jeff for the background.) This has the consequence that lots of the posts of Gonzalo Medina show this
instead of the intended image. At the moment I see two possible ways to fix this, one even worse than the other:
stack.from all the image links in Gonzalo's posts. This would bump all the posts; moreover, it wouldn't move the images to the
stackaccount, so they would be lost sooner or later.
stack.from the image links and re-upload all the images via the "add image" button. This would also bump all the posts, and it would be even more work.
So what can be done about it?