Hi…
I was wondering if its possible to get/call the TopDownMovement Behaviours Speed property, as I want to Display it on Screen with a Text Object.
Oop, Nevermind, I seem to have found it.
Its Under Movement > TopDownMovement > Speed.
Hope This Helps Someone 
We call this an expression.
FYI, all the expressions should be listed here: Expressions reference [GDevelop wiki]