The video player shows the currently loaded video, and allows you to play it back and view the splits you've made.
This area shows information about the currently loaded video.
Here you define how you want to split your video: into segments of a specific length, into some number of equal-length segments, or according to the clips you specify in the clip list
Here you set certain settings regarding how splits will be made in general.
These settings allow you to control how your split files are saved, including how the videos will be compressed by QuickTime
Clicking this tab will bring you to the clip list, where you can define custom splits to make in your video.