packages/docs/docs/recorder/editing/b-roll.mdx
You can overlay your recorded scenes with additional video or photo footage by adding bRoll elements in the right sidebar.
Add the footage you want to use to the public folder and select it from the bRoll drop-down menu for the scene you want to overlay.
Configure when and for how long to play an asset by adjusting the from and durationInFrames values.
The from value is relative to the scene to which you are adding the B-roll and defines the frame from which the asset is to be displayed.
The data that you add in bRoll is postprocessed to enforce the following rules:
These constraints are defined in remotion/scenes/BRoll/apply-b-roll-rules.ts.