AutoPager is described as 'Automatically loads the next page (inline, using javascript) when you reach the end of a page. It works on a variety of sites including Google, Yahoo and Youtube amongst many, many others. If you find a webpage that it doesnt handle then you can make your own rule that' and is an app in the web browsers category. There are four alternatives to AutoPager for a variety of platforms, including Google Chrome, Opera, Mozilla Firefox, Mac and Windows apps. The best AutoPager alternative is AutoPagerize, which is both free and Open Source. Other great apps like AutoPager are Autopatchwork, PageZipper and Pagetual.
Works better than autopager so far but I only started using today and seems to require pressing its icon somewhere near address bar (left of address bar or maybe right depending on any other add-ons you have in FF) so doesn't appear to be automatic. as you page down, another page downloads then appears.