Sample of an evening presentation without visuals, but with significant Q&A session.
Visual aids (powerpoint for example when available) are edited into the video. With long presentations, some cruel editing of the material might be required, or perhaps on-screen help as to where we are in the sequence; or graphic overlays to aid clarity of the subject.
Here (in French), an evening of presentation is divided into overview, details and responses to questions - by question. Above is the overview section of 15 minutes, the full program is available on the YouTube channel playlist - all sections are public.