Originally posted by timw4mail The reason is that the images in question are hosted on http, not https. There's a setting in the control panel for it.
The setting is whether to allow "mixed" http/https content for forum pages you view. This is generally not a good feature to disable, at least not from a security perspective.
Better is for the posting user to manually edit the image URL to be https (assuming the remote server supports such...most do). That way all users will see that users share rather than just those who have disabled the default mixed content setting for this site.
Steve