Painting a region was Gen-2's answer to shot-level control

The shot

In October 2023, Runway shipped Motion Brush, a control layered onto its Gen-2 image-to-video model. Runway's own help-center article, preserved by the Wayback Machine after the live page was retired, documents the feature as a way to 'gain precise, element-by-element compositional control' over an image-to-video generation, rather than leaving every part of a frame to move however the model chooses.

What the documents show

The archived article lays out the mechanism step by step: after generating or uploading a source image, a user clicks a paintbrush icon next to the separate Camera Motion control, then paints directly over the region of the image they want to move, with a brush and eraser to refine the selection. Once an area is selected, the documentation states the user can 'control motion in the horizontal (x), vertical (y), and proximity (z) directions,' selecting 'up to one option from each modifier' before saving. This is Runway's own product documentation of a shipped, licensed feature, not a demo reel, which makes it a documented capability rather than a promotional claim. A separate, current Runway support article on Gen-2 deprecation confirms the feature's scope going forward: it states 'Motion Brush is a feature specific to the Gen-2 model, and is not available on newer models,' with Runway adding that comparable results are 'now be accomplished directly through prompting' on later models.

The workflow

As documented, the tool sat inside Runway's existing Text, Image, and Image-plus-Description modes: a user generates or supplies a still, opens the Motion Brush editor, paints one or more regions, assigns each a direction and intensity, and only then runs the generation. Painting several regions with different modifiers let an operator direct, say, water rippling in one part of a frame while a foreground subject stayed still, a level of control distinct from the separate Camera Motion setting that moved the whole frame as if a camera were moving through it.

What the tool does not change

Runway's own documentation scopes Motion Brush to localized, painted regions with three directional modifiers, not to full camera choreography, continuous performance, or scene blocking; the help article never claims otherwise. The later deprecation notice is itself evidence that this specific control did not persist as the industry's answer to directable motion; Runway says newer models absorbed the same creative intent into prompting instead, which still leaves a human writing and judging that prompt.

• Is 'motion control' in a vendor's materials describing localized painted regions or full camera movement?
• Does the feature you are reading about still exist on the model you would actually use?
• What decision about where motion belongs in a frame is still yours to make before you paint or prompt?

Motion Brush documents an early, concrete attempt to give a generation tool shot-level direction rather than a single prompt, and Runway's own later notice that the feature was retired in favor of prompting is as informative as the original launch: a specific interface component came and went, while the underlying creative decision, where should this frame move, stayed with the operator throughout.