i think I know your issue 
you loaded 2 videos (or more) but you selected only one video in the input section (you see you highlighted only one video). you need to select all your videos by clicking on them when holding the Ctrl (or Shift) button, or by Ctrl + A (select all). once you do that then you need to select the presets, action you want to do. because based on your screen shot you only had set one video with your settings to be processed. you can also verify this by see in brackets on the “export” button the number of exports.
