`devpage video` records a deck to mp4: GPT-Live reads each slide's notes word
for word, for the deck's audience and in its tone, while Chrome shows the slides — 1920 × 1080,
no silence longer than a second.
```
$ DEVPAGE_OPENAI_API_KEY=sk-... devpage video talks/launch
slide 1/6
...
Launch.mp4
```
Teaches it: [Making a video](../boxes/viewer/making-a-video/README.md).