Video File Format : How to change it ?

Hi !
Recently i read in the help section of NL2 that we could change the video file format. (look at screenshot in attachment)
By default i know it's MOV and i find this format very "heavy" (sorry for bad English i'm french) and i would like
to change it to MP4 so my video captures take less space...
So i go to the "video export" tab in the setup section, and there's no "FORMAT" Button...
Can you help me ?

Try checking for a recent update. Mine only displays AVI and MOV formats, no MP4.