The scroll position plugin is used to record how far users scroll down on a web page.
An eventrequest will be fired as soon as the visitor leaves the page, for example by clicking on a link. In the request the scroll max scroll depth is transmitted as a percent number. You also have the option to transmit the page height, so you can calculate the max scroll depth in pixels with a custom formula.
This plugin only works with pages that have a defined height, it won't work on endless-scrollpages.
More information you can find in the documentation inside the zip file.