Film what you don't have

It's easy to assume NextDemo can only point at your app. It can point at anything that renders in a browser — and your agent writes HTML. So the screen you haven't built, the slide between two takes, the spreadsheet you need on camera but don't want to be real: describe it, and the agent builds a page for the camera to film.

What a stub is for

• Slides and title cards — an intro frame, a section break, a closing call to action, set in your own type and color.
• Screens you haven't shipped — demo the feature before it exists by filming a faithful mock of it.
• Stand-ins for other apps — a spreadsheet, a doc, an inbox, a chat — enough to carry the story, showing only the part that matters and none of the clutter around it.

Why a stub beats the real thing

A stub is source code, not a screen grab — and that changes what the footage is worth.

• It doesn't age. Someone else's product redesigns on its own schedule; the day it ships a new nav, your recording of it looks dated. A stub is frozen exactly as you built it, and moves only when you decide.
• It shows only what matters. No login, no cookie banner, no sample data to scrub, no rows you didn't want on camera — the frame carries your point and nothing else.
• It moves with your product. Rename a feature, shift your brand colors, reword a headline — the agent edits the stub in the same pass as the rest of the change. The video stays true while the world around it shifts.
• It needs no editing. The slide, the stand-in, and your app are filmed by one script, so NextDemo renders the finished mp4 — transitions and all. Nothing to export and stitch back together in an editor afterward.

Source, not a folder of stale assets

The old way of putting a slide or a stand-in screen in a demo means an asset to prepare — a Keynote deck, a mockup, a screenshot doctored to the right sample data — then somewhere to keep it, a version to track, and the chore of redoing it every time the product moves. Assets like that rot in a folder.

A stub skips that pipeline. It's a page of source in your repo, versioned with the recording script, edited by the agent in the same pass as the rest of a change. You hold the controls: it looks exactly as you meant, changes only when you say so, and re-renders current on every run. No asset library to babysit — the demo keeps up on its own.