How to make a narrated demo video of a bug on Mac
Hold the talk key, describe the bug, and press ⌃⌥S at each moment worth showing. When you let go, fab makes a demo video: your grabs in order with your words as captions.
You need: fab 0.2.14 on macOS 26 or later, Apple silicon
Updated:
Steps
Step 1
Hold the talk key and start explaining
fn
Talk through it as you would on a call: what you did, what happened, what should have happened. Tap twice for hands-free if it’s a long one.
Step 2
Grab each moment as you mention it
⌃⌥S
A picture for a state, or press V in the picker for a short video of the bug happening, up to 2 minutes.
Step 3
Let go
Your words land where you were, and fab makes the demo video. A card in the corner plays it.
Step 4
Mark up a grab if it needs it
Click a grab, draw a box or an arrow, and press ↵. fab rebuilds the video with your marks.
Step 5
Drag the video where it goes
Drag it from the card into an issue, a pull request, or a chat. It’s also in History with the take.
Tips
- Video grabs play in time with your voice, so you can show the bug and explain it at once.
- Grabs in low definition (H in the picker) make smaller files.
- Find old videos in History with the “Demo video” filter.
Questions
- Where is the video made?
- On your Mac, from your grabs and your words. Nothing is uploaded.
- Do video grabs record sound?
- No. A video grab records the screen and the pointer only; your voice from the take is what narrates it.
- Can I change the video after it’s made?
- Mark up any of its grabs, from the take or from History, and fab makes the video again.