It's easy! We will provide you or your DVD author with a master tape. Channels 1 and 2 are the main program audio, and Channel 3 will contain a mix of both the program audio and the descriptive narration. Channel 3 should be captured and exported separately from 1&2, then set as the A2 audio stream on the DVD authoring software. The key is, don't cross the streams.
If you have any more questions or need more detailed information, please don't hesitate to contact us.