This is the bookmark widget, with it you can bookmark points of videos. When you'll have bookmarked one of these points it will appear in the list. To remove a bookmark click on the small cross at the left of that bookmark.

When marking a point you can fill a custom title in the textbox before creating the bookmark, when you'll mark the point it will be marked with your custom title. You can also choose to mark the beginning of the video by ticking the checkbox.

To begin click on the Bookmark tab.