Using iFlicks is is quite easy to add chapters to your video files. Checking and editing chapters for a video can be done using the Chapters sidebar.
Editing and updating chapters is possible with the iTunes compatible and all encoding presets.
Adding or removing chapters can be done by using the + and - button at the lower left of the Chapters sidebar.
If you want to add chapters all # minutes you can do so using the advanced button at the bottom right of the Chapters sidebar. In the advanced menu you will also find an option to remove all chapters or import chapters from an external file.