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An AI video model is like a very talented crew that has never met you. It will do exactly what the brief says, beautifully, and fill every gap with its own taste. Sometimes that taste is great. Often it's generic: a slow pan, a vague smile, a voice-over that sounds like every other ad.
The fix isn't longer prompts. It's briefs that make the decisions a director would make, so the model doesn't have to.
What a video model needs to know
A good brief answers six questions. If one is missing, that's where the video goes generic.
| Question | Why it matters | Weak | Strong |
|---|---|---|---|
| What is the idea? | Gives every shot a purpose | "Show the product" | "A commuter realises she left her wallet at home, and it doesn't matter" |
| What must stay exactly the same? | Stops the product drifting | nothing | "Keep the tan leather, the brass snap and the stitched logo exactly as in the photo" |
| What happens, in order? | Pacing and story | "Nice shots of the case" | "0-2s phone slides out of a pocket, 2-5s thumb opens the card slot..." |
| How does it look? | Style and realism | "Cinematic" | "Handheld phone footage, daylight, real skin texture, no film grade" |
| What do we hear? | Mood and attention | nothing | "Street noise, a soft click as the case opens" |
| What is said? | The message | "Talk about the benefits" | "I haven't carried a wallet since March." |
Describe actions, not adjectives
"Premium", "stunning" and "beautiful" give the model nothing to film. Actions do.
- Instead of "a premium product shot", write "the camera slowly pushes in on the stitching while a thumb runs along the edge".
- Instead of "a happy customer", write "she laughs, taps the case twice and slides it into her back pocket".
If you can't picture it, the model can't render it.
Lock the product down
The most common complaint about AI product video is that the product changes: the logo moves, the colour shifts, a button appears that doesn't exist. Two habits prevent most of it.
- Describe what's in the photo in plain words: material, colour, shape, where the logo sits, any text on it.
- Say what must not happen: "Do not show the back of the case. Do not add details that aren't in the photo."
The model can't invent a side of the product it has never seen, and it shouldn't try.
Write the voice-over for a mouth, not a page
Marketing copy reads well and sounds awful spoken. A few rules:
- About 2.5 words per second. A 10-second ad fits roughly 25 words.
- One idea per line. Short sentences, contractions, no lists of features.
- No words nobody says out loud. "Elevate", "unlock", "revolutionary".
- Read it aloud. If you run out of breath, cut.
A full before and after
Here is a real brief for a leather wallet case, first as most people write it, then rewritten.
Before
Create a premium, engaging UGC video showcasing our high-quality leather phone case. Show the elegant design and highlight its key features and benefits. Make it cinematic and eye-catching with a call to action.
Every word in that brief is a request for the model to decide for you.
After
Idea: A woman at a busy coffee counter pays with her phone and realises she hasn't needed a wallet all week.
Keep exactly: Tan full-grain leather case, brass snap on the right, embossed logo lower back, three cards visible in the slot. No other sides shown.
Shots: 0-2s close-up, her hand pulls the phone from a coat pocket. 2-5s she flips the card slot open with her thumb, two cards visible. 5-8s she taps to pay, small nod. 8-10s the case goes back into the pocket.
Look: Handheld phone footage, morning daylight through a window, real skin texture, no colour grade, no slow motion.
Sound: Café noise, the snap of the case.
Voice-over (her, to camera): "I stopped carrying a wallet in March. Cards live here now. That's it."
Language: English.
Same product, same model. The second brief makes every decision a director would make and leaves the model to do what it's good at: making it look real.
Let the AI write the first draft
You don't have to write this structure from scratch every time. Write with AI in AdVideoLab studies your product photo, reads your brand voice and writes a brief in exactly this shape, paced to the length you chose. Edit it like you'd edit a copywriter's draft: keep the structure, sharpen the hook, cut anything you wouldn't say.
If you'd like to see what it writes for your product before signing up, paste a product page into the free ad script generator.
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