re: Production company wants to offer money to use part of my video-update agreement

Exclusive means they essentially own your footage. They own the rights and no one else can ever use it except their company. Commercial rights (at least in the music biz) they borrow your footage,and "x" number of people are allowed to view it.

What I'm saying here is that if they want exclusive rights to your footage make them pay a steep price for it because it means they'll use it for other commercials as well.