I don't mean to hijack this thread, and I will try to be brief.
You can open a video file from the "File" menu, click "Open Source...", and navigate to and select the file. Drag and drop is also supported, so that you can drag your video file to the MetaDoctor window or icon to open it.
To add a chapter, use the video pane to move the playhead to the spot in the video where you want a chapter, and click on the "Add" button, use keyboard shortcut Command-I, or simply double click on the video. To edit chapter titles, click once on the chapter in the chapter table to select the chapter, then a second time on the title cell to select it for editing.
Click on the "Save Metadata" button or the "Save" menu item under the "File" menu. The chapters and any other tags you added are written directly to the video file.
iDVD will read the chapters.
You can contact me by email via the support page on the MetaDoctor web page if you need further assistance.
http://starwaresoftware.wix.com/metadoctor