I'm unsure how the path to ffmpeg is detected(or how the path must be registered). Is it something like the "add to path" part here? http://blog.gregzaal.com/how-to-install-ffmpeg-on-windows/ Or should I add a path-string-entry in the add-on Preferences just for Windows?
Fork: https://github.com/tin2tin/blender_addon_push_to_talk/blob/master/__init__.py
Showstoppers: