DEV Tools chrome

I want to know how I can follow along in this short lecture Im having a hard time replicating the information he is displaying on his screen or finding the properties he is referring to.

Udacity Intro Ajax Course

Im not sure everyone can just open this link that i am referring to without signing up, but I know it is a free course.

I see when I scroll down more requests are loading but dont understand how to find the exact request that corresponds to the exact section of html that the page is loading. Also if you know of any other tutorials that demonstrate how to see and inspect ajax requests as the page is loading please attach them to this thread because I didnt understand his tutorial.