Export options - all, motion, active_objects

**Describe what you are trying to accomplish and why in non technical terms**
I'm trying to export only relevant footage.

**Describe the solution you'd like**
It would be awesome, if it's selectable what should be exported like you can choose what should be recorded. Since I need to record all I cannot change that. Currently all is exported. Would be nice to be able to export only the seconds where motion or active_objects are detected.

The issue requests selectable exports for all footage, motion, or active_objects, but names no files or tests. Start by locating the export and recording-selection entry points, then define how each option selects footage and verify that the requested export modes work.

Written by the indexing model from the issue text.