When inserting media in Firefox, there seems to be a problem.  The media shows up correctly in the insert popup window.  However when it is in the editor itself, it looks like it is inserted as Flash.  I have tested this with my own CE config as well as the one on this website and am able to reproduce the problem.  I have all the necessary plugins installed in Firefox so the plugins are not the issue here.  You can view a screenshot of this problem at : this website.