[片段参考] + 将参考片段视为摄像机从未停止录制。在其之前立即生成缺失的几秒，使用完全相同的镜头语言、光线、节奏、摄像机运动和连续性，结束在…

Here's the base prompt I use for every "Reverse Extension":

[clip reference] + Treat the reference clip as if the camera never stopped recording. Generate the missing seconds immediately before it with identical lens language, lighting, pacing, camera movement and continuity, ending on a frame that seamlessly connects to the first frame of the reference clip. Build a natural cause-and-effect sequence that logically explains why the reference begins exactly as it does.
Preserve the same characters, wardrobe, nvironment, camera language and visual continuity throughout.
The final frame must visually match the first frame of the reference clip as if it were one uninterrupted take + [prompt scene ]

This is the foundation.

You can either let Seedance decide what happened before…

or completely direct the missing sequence yourself.