eliZZa, check your email.
I sent an email to you about an hour ago to elisabeth.w*****@gmail.com
Thanks!
^F^
This problem appears to be limited to the German web host “Domain Factory” due to the way they set up their servers. As you noted, the way the host configures them prevents any media item, even if it’s uploaded by the admin in the WP-admin back-end, from displaying properly unless the WP installation is modified to work around their server config.
I sent you a modified plugin file that should resolve the problem on your host. We’ve also added it as a work item for version 0.1.9 in case there are other users signed up with them. Here’s the tracker entry: https://www.pivotaltracker.com/story/show/16141897
Thanks!
^F^