Motion Transfer vs Character Swap vs AI Video Editing: Which One Do You Need?
Three ways to change a video with AI. What motion transfer, swap and AI video editing each do, when each one wins, and real examples for every mode.
Three Ways to Change a Video With AI
Video-to-video AI starts with footage you already have and gives you back new footage. That covers three different jobs. You want a clip's movement with a different performer. Or the performance is right and one thing in the shot is wrong. Or nothing is wrong and you want different light, a different frame or fewer people in the background.
Genjudo, Genfire's video-to-video studio, splits those jobs into three modes, all running ByteDance's Seedance 2.5 reference-to-video model: Motion transfer, Swap and Video edit. Alongside them sit Extend, which continues a clip past its last frame, and a separate Motion Control tab that runs Kling 3.0 Motion Control.
| Motion transfer | Swap | Video edit | |
|---|---|---|---|
| What stays | The moves, timing and camera | The take, except the one thing you swap | The take, except what you describe |
| What changes | Who performs, from 1 to 2 images | The product, the outfit or the location | Light, framing, clutter or colour |
| What you add | A clip and your character images | A clip and an image of the new item | A clip and a sentence |
| Best when | You like the movement, not the performer | You like the performance, not one element | You like the shot, not how it looks |
The quickest test is one question: do you want to keep the footage, or only the movement? If only the movement, it's motion transfer. If the footage, it's Swap or Video edit, depending on whether you're replacing a thing or changing a look.
Motion Transfer: Same Moves, New Cast
Motion transfer reads the movement, timing and camera of a clip and has your own cast perform it. You add the clip and one or two images, and Seedance 2.5 generates a new shot with your character in it. The original performer doesn't appear in the result; only what they did carries over.
This is the mode to use when you want to replace the character in a video. Rather than editing a person out of existing footage, you generate the shot again with your character performing the same action. Presets cover the common setups:
- Exact transfer: the same motion, camera move and framing on your character.
- Dance, beat for beat: footwork, arm timing and weight shifts locked to the reference.
- Product in hand: the reference's handling and camera move, with your product from the image.
- Two characters: two images cast in two roles, foreground and behind.
- Garment on model: your model performing the move while wearing your garment.
- Motion in a new place: the same move, set in the location from your second image.
When it wins: you want to reuse a move without the original performer, or have the same action performed by several characters. It's also the mode for brand mascots and original characters, which have no footage of their own until you make some. The dedicated walkthrough is on the AI motion transfer page, and dance gets its own guide on the AI dance video generator page.
Swap: Keep the Take, Change One Thing
Swap edits the clip you already have. You pick what to replace (the product, the outfit or the location) and add an image of the new one. The rest of the take stays as filmed: the same performer, the same performance, the same camera.
Three concrete cases:
- Swap the product. A creator filmed a great review holding last season's packaging. Swap in an image of the new pack, and the hands, the delivery and the lighting stay the same.
- Swap the outfit. One lookbook clip, several colourways. Run Swap once per garment image and you have a clip for each.
- Swap the location. A product demo filmed in a spare room moves to the location in your image, with the performance untouched.
When it wins: the performance is the hard part and you already have it. Reshooting a good take to change one prop is expensive; Swap changes the prop and keeps the take. More on this mode is on the AI character swap page.
Product in hand: Swap or motion transfer?
Both modes can put your product in someone's hand, and the choice comes down to whose footage it is. If you own a good take of your own presenter, use Swap and keep everything they did. If you only have a reference clip of the handling you want, use the Product in hand motion transfer preset to generate a new shot with your product, the same handling and the same camera move.
Video Edit: Describe the Change
Video edit changes how a shot looks rather than what's in it. You describe the change in a sentence, and anything you leave out stays as filmed. Presets are grouped by the kind of fix:
- Light & weather: golden hour, neon night, fog and rain.
- Reframe: punch in, widen the shot, go vertical, change the lens.
- Clean up: remove background people, remove logos and text, remove an object, steady and de-clutter.
- Colour & grade: change the season, 1970s film stock, black-and-white noir.
Four examples:
- Relight to golden hour. A product walk-through filmed at noon looks flat. Relight it to late golden hour: warm, low sun from one side and long shadows falling across the floor.
- Go vertical. A horizontal interview needs a version for Reels. Reframe it to 9:16 so the subject stays in the frame.
- Remove background people. A great street take has strangers wandering through the back. Remove them and rebuild the street behind.
- Change the season. A summer clip for a winter campaign: bare trees, snow on the ledges, cold light.
A tip for writing your own edits: name the direction of light and what the shadows do, not just a mood. "Warm sun from camera left, long shadows falling right" gives the model more to work with than "make it cosy". And end the sentence with what must not change, such as "keep the subject, motion, framing and timing exactly as filmed".
When it wins: the content is right but the look isn't. If you'd otherwise reach for a reshoot, a relight or a rotoscope, try Video edit first.
Extend: Keep the Shot Going
Extend continues a clip past its last frame. An establishing shot that cuts away a second too early, a product rotation that stops before the label comes round, a motion transfer result that ends before the action does: Extend picks up from the final frame and keeps going, and you can write what should happen next.
Seven Jobs, Matched to a Mode
| The job | Use | Why |
|---|---|---|
| Your product in a creator's hand, using their footage | Swap the product | The performance stays as filmed |
| Your product handled the way a reference clip shows | Motion transfer, Product in hand | You keep the handling, not the footage |
| One lookbook clip in four colourways | Swap the outfit | One take, one run per garment |
| A daytime clip that should feel like golden hour | Video edit, Light & weather | Changes the light, keeps the take |
| A horizontal clip that needs to run on Reels | Video edit, Reframe, Go vertical | Reframes to 9:16 around the subject |
| Strangers walking through the background | Video edit, Clean up | Removes them and rebuilds the scene |
| A shot that ends too soon | Extend | Continues past the last frame |
Where a Timeline Editor Fits
Genjudo changes what's inside the frame. Cutting several shots together, adding captions, laying in a voiceover or music is a different job, and that's what the AI video editor is for. A common flow is Genjudo for the individual shots, then the editor for the cut.
Sources, Direction, Sound and Cost
- Sources. Upload a clip, or paste an Instagram reel link to use the reel as the source.
- Length and takes. Results run 4 to 30 seconds, with 1 to 4 takes per run.
- Direction. An AI director can watch your clip and write a shot-by-shot direction, or you write it yourself. References appear in the prompt as
@Video1,@Image1and@Image2. - Sound. Keep the clip's sound, have Seedance write AI sound, or return the result silent.
- Cost. Every run is billed per second of output from one Genfire credit balance, shared with 80+ image, video and audio models, and the exact cost is shown before you run. Credit packs start at $19 on the pricing page.
For a second model's take on motion, the Motion Control tab runs Kling 3.0 Motion Control; the Kling V3 page covers that family. If you're comparing Genjudo with other tools, see Genfire vs Viggle. And if you need a character to cast, build an original one in the AI Influencer Studio.
Use Footage and People You Have the Right To
Use clips you shot, licensed or have permission to use, and only cast people who have agreed to it. Your own original characters are the safe default.
FAQ
What is video-to-video AI?
Video-to-video AI takes an existing video as input and produces a new one, either by carrying its motion over to a new cast or by changing part of the original footage. Genjudo does both on Seedance 2.5, through Motion transfer, Swap, Video edit and Extend.
How do I replace a character in a video with AI?
Use motion transfer. Add the clip and an image of your character, and Seedance 2.5 generates a new shot in which your character performs the same moves with the same timing and camera move. Only cast people who have agreed to it; your own original characters are the safe default.
What is the difference between Swap and Video edit?
Swap replaces one thing in the shot (the product, the outfit or the location) with the one in your image. Video edit changes how the shot looks, such as its light, framing, clutter or colour, from a sentence you write. In both, everything you don't change stays as filmed.
Can I change the product in a video without reshooting?
Yes. Swap the product replaces the product in your clip with the one in your image and keeps the performance, hands, lighting and framing as filmed.