How to create a static post at the top of the page?

I have manually inserted code into the content-main.php file so that a post appears just inside the square grid but outside of the post loop. 

I need the expanded showreel you see in the top left to always stay there in its open state - HOWEVER, when scrolling down the page, the infinite scroll refreshes and keeps displaying more of the same post over and over again at the bottom of the page. 

Scroll down and you will see an example here - http://www.lightcreative.co.uk/new/

Thank you - James