He is talking about a situation when during preview, icons appear as
:aether
..instead or
. So you see only the code, not the images.
This only happens during preview mode, and only with some of the browsers. I think majority of browsers show it correctly.
This will probably be fixed in later versions of our forum software, which will hopefully be installed very soon, and which will fix tons of other issues as well. We will also get many new plugins. It's going to be awesome.