Yes. And your guy has to have an AE version that matches your AE/PP versions as well, or it won't work. And if they're older versions, they may not work at all together.
Not to mention you'd need all the source footage as well. And you'd probably have to reconnect the media.
Are you SURE you want to try this stunt? Why not just have the guy render out his AE work?
Agree with Dave. No offense, but your "I have no clue" question is a clear sign that you are entering dangerous territory and should not even think of it if you are on a deadline. You'd quite likely be in all kinds of trouble getting things to work the way you want.