Runway swaps actors in already-shot video without a reshoot

Runway has added the Character Swap app to App Studio: it replaces the character or the setting in an already-shot clip while leaving the original motion untouched. The audio can be kept from the original, carried over to the new scene, or replaced.

For production, this moves recasting out of the soundstage and into post. The scene has already been performed; all that changes is who is in it and where it takes place. Runway names outright the scenario the app was built for: releasing versions of a single clip for different markets with a suitable actor for each, or rebuilding a scene without arranging a reshoot. The description of App Studio's capabilities mentions swapping products or characters for two dozen markets and SKUs without re-rendering the clip.

What the user specifies

The new character is specified either with an image or with a text description. According to the official description, the app rebuilds the source video with the new character, relying on a keyframe built from a depth map and on the Seedance 2.5 video model. The depth map here is what keeps the scene geometry and composition intact, while the generation itself is handled by a third-party model rather than Runway's own line-up.

The apps have moved into a new shell

The former Runway Apps catalogue has moved into App Studio: according to the company, users need to do nothing — the apps can be used as before, or any of them rebuilt into your own version. Character Swap is listed among the built-in apps Runway released alongside App Studio, next to Precise Edit, AutoComp, Product Portfolio, 3D Camera Control and Runway Pro.

App Studio is a builder in which the user describes the desired tool in words and the platform itself writes, tests and hosts the app with an interface of its own; the code remains available to inspect. Inside, Runway's image, video and audio models are available, as are Brand Kits, Workflows, assets and workspace references. A finished chain from an agent session or a workflow is turned into an app in a single action: the prompt, the set of models and the settings are locked in, and only the needed fields remain exposed.

The point of that packaging is obvious to anyone who has run a pipeline. The recipe that produces the required result usually lives in one person's prompts and settings. An app turns it into a tool for the whole team, and an update to a workflow, references or a Brand Kit shows up in new outputs.

Whoever presses the button pays

App Studio itself is included in every paid plan with no separate purchase and no surcharge, but building, running and hosting apps draws credits from the account's existing balance. Each app shows its own consumption so that spending can be tracked per app and per workspace. A free account can run the built-in apps and those shared with it, while building your own requires a paid plan. If an app is published via an open link, the visitor pays for their own generations and the owner pays only for the build, their own runs and hosting. Character Swap can be opened from App Studio's catalogue of built-in apps.

Access is arranged just as granularly: an app is private until its author shares it, teams and enterprise customers can open it to specific people, a project or the entire workspace, and administrators see usage and control whether public links are allowed. Models disabled in the admin console are unavailable inside apps as well.

Runway is selling the assembly, not just the model

A company that built its reputation on its own generative models is putting an app in its own catalogue where generation is handled by Seedance 2.5. By that logic, the product becomes the bundle: preprocessing, interface, access rights, hosting and billing.

What to check on real material

The app carries over the source's motion as is — simultaneously its strength and its limitation: the quirks of the shoot stay in frame along with the new character. A demo clip is no basis for judging how Character Swap holds a long take; that will have to be checked on your own material.

Why tools like this are appearing right now

Over the past year, swapping a character in finished video has turned into a product category of its own: similar features exist both in specialised services and in builds on open video models. The difference between them rests less and less on generation quality and more and more on how predictably the tool fits into the working day. Hence the form Runway has chosen: a narrow app with a handful of fields, access rights and credit-consumption tracking.

If the trend continues, the first to feel the change will be those doing ad localisation and multilingual versions of clips: there, a reshoot just to change the actor has always been the most expensive line in the budget. After that the question will probably shift into the legal realm — rights to a performer's likeness and voice, consent to recasting, labelling of generated versions.

Would you trust Character Swap with replacing an actor where you used to do rotoscoping and tracking by hand? What would have to line up before you handed it a real project?