Final answer:
A DVD provided at the end of a speech is a takeaway or supportive media that complements the speech and offers deeper understanding or follow-up material for the audience.
Step-by-step explanation:
The DVD given to listeners at the end of a speech is an example of what the book might term a supplement or supportive media. It serves as a takeaway that the audience can refer to after the speech, which can reinforce the speech's main points or provide additional information for a deeper understanding of the topic. What the book mentions about a compact bibliography, an epilogue, and summary presentations all serve similar functions—they supplement the main content and aim to provide completeness, additional context, or follow-up material for further learning and reflection.