To cover deep post routes, run Cover 4 as said above. However, I don't press coverage and move anyone down like he does. I just simply show blitz. The safeties are close to the LOS, which means they take longer to drop back into their deep blue zones. Because of the extended time taken, the safeties back into their zones as the post routes develop, so they are at about the same depth when the pass is made. Most of the time, the safety will make the easy INT or your opponent will wise up and not throw it to him.
Word of advice for cover 3 users. Manually move each defender who is in a hook so they are lined up like this. The LB on the left should be to the outside of the offensive tackle and close to the LOS, then playmaker him to a hook zone. Move the MLB into the A gap (on either side) and close to the LOS and playmaker him to a hook zone too. Finally take the SS and put him at LB depth, to the inside of the right slot receiver (if there is one, if not, pretend there is) and playmaker him to a hook zone also. This way, each of the 3 hook zones cover a different part of the field, but not too far apart to where there is a gap to throw into. This also can be set up the same way to bring heat. Try it out.