The Load list of sites from URL field allows you to obtain the list of sites to block from a URL (e.g., a text file on a web server). The list will be loaded every time a new browser window is opened. This feature is useful if you have LeechBlock installed on multiple machines and want to avoid having to update the settings on each machine in turn whenever you need to change the list of the sites to block. (Note also that if you put
$S in the URL it will be replaced with the number of the block set and
$T will be replaced with a UTC timestamp in milliseconds. The latter can be useful for avoiding caching problems.)
If you don’t understand any of this then you almost certainly don’t need it! If in doubt, just leave the Load list of sites from URL field blank.