Can I record a virtual screen with FFmpeg?

Yes. A connected BetterDisplay virtual screen can be captured as a screen by another recording app. With a macOS FFmpeg build that includes AVFoundation input, enumerate the available capture devices and select the virtual screen from that list.

First create and connect the virtual screen, then move the content you want to record onto it. List FFmpeg’s devices:

ffmpeg -f avfoundation -list_devices true -i ""

Identify the screen you intend to capture before recording. For example, if its video-device index is 2, this records it without audio:

ffmpeg -f avfoundation -i "2:none" recording.mov

Replace 2 with the index from your own list. It is an FFmpeg capture-device index, not a BetterDisplay display identifier. Grant macOS screen-recording access to the capturing process or its host when requested. Move the windows you want to record onto the virtual desktop, then check a short sample recording to confirm that you selected the right screen.

FFmpeg’s AVFoundation documentation covers device selection, capture frame rate and cursor options. FFmpeg performs the recording. BetterDisplay’s HTTP and CLI integration configure app features but do not themselves provide a video stream.