The one thing that must not change
In a product ad, the product is the subject and the constraint. Everything else can be interpreted freely; the product has to survive every shot recognisably identical, because it is the thing the viewer is being asked to buy.
Generative video is not naturally good at this. Each generation is an independent interpretation, and independent interpretations of a product differ in exactly the details a customer notices.
Asset-lock, before anything moves
Establish a consistent product reference first — a controlled set of views that agree with each other — and treat it as fixed for the rest of production. Every subsequent generation is anchored to it.
Doing this first is what separates output that reads as a product ad from output that reads as a product-shaped animation. It is also the step under time pressure that is most tempting to skip.
Storyboard to a frame count
A fifteen-second runtime is a real constraint or it is decoration. Storyboarding to a fixed number of frames converts generation from an open-ended request into a series of specific ones, which is both more controllable and considerably cheaper.
It also front-loads the creative decisions to the point where changing them is free.
Physical products need different handling than digital
Physical goods reward motion that emphasises material and form. Digital products — software, apps — have no physical presence, so the equivalent subject is the interface, and the same hyper-real treatment applied to a UI looks absurd.
Deciding which category you are in before choosing a visual approach avoids a whole class of wasted generation.
Harvest, then cut
Generate more than you need and select deliberately. Expect to discard a meaningful share, including things that took effort. The willingness to cut a finished piece for being weaker than its neighbours is what holds the average up, and the average is what the audience experiences.