That mini jack plug on the camera is for an external speaker with amplifier, for exemple pc speakers..
There is an built in microphone inside of the camera itself.
With the right software you are able to use the 2 way audio function in the camera as long as you have speakers with its own amplifier connected to the camera..
All though modifications must be made with the microphone in order to get a completely clear sound as there is ALOT of statics being picked up, also it gets amplified when you move the camera around..
But it is possible to relocate the microphone and in addition to that use a ferret ring on the positive wire from the microphone.
I relocated my mic from the camera with a spring wire to the camera mount.. now it works perfectly.