That guy is completely wrong. It is when the returner is going to catch the kick and the kick team gos past the 5 yard line before the returner touches the ball.

It's when the receiving player calls for a fair catch and a player from the kicking team interferes with the opportunity for him to make an uncontested catch (usually a two yard halo around the receiving player). Hope that helps

Its the NFL. If a returner calls a fair catch usually during a punt and the defensive player interfers such as touching him or pushing him so he cant make the fair catch, it is called FAIR CATCH INRERFERANCE.