Forwarding a single port from one network adapter to another?
According to what you're trying to achieve, your rule is in a wrong position.

This Source will show you how to set up a rule.
However, you're navigation FROM:


  sudo ipfw add 100 fwd 10.37.129.3,3389 tcp from any to any 3389 in


Please don't hit me with a stick, I'm unable to forward this on my Mac to test.