HotLink protection prevents other websites from directly linking to files on your website. Other sites will still be able to link to any file type that you don’t specify (ex: html files). An example of hotlinking would be using a tag to display an image from your site from somewhere else on the net. The end result is that the other site is stealing your bandwidth. You should ensure that all sites that you wish to allow direct links from are in the list. This system attempts add all sites it knows you own to the list, however you may need to add others.