Why it happens, and what changes it.
The thumbnail is the still image Rekorder shows for a recording — on its card in your Library, as the paused frame on the video page before you press play, and embedded in share emails. Rekorder generates it automatically from a moment near the very start of the recording, so a black or unrepresentative thumbnail almost always comes from what was actually on screen at that point, not from a broken image.
How the thumbnail is generated
- Rekorder creates the thumbnail itself, from the video, once the recording finishes processing after you stop it.
- It's taken from close to the beginning of the recording — typically within the first couple of seconds.
- There's no setting to upload or pick a different thumbnail yourself. To change it, you change what the video looks like at that point (see below).
- Editing a recording (cutting, reordering, muting) doesn't touch the thumbnail until you actually render it. A draft leaves the existing thumbnail as it is; running Apply & render regenerates the thumbnail from the new beginning of the edited video. See Save a draft vs Apply & render.
Why the thumbnail is black
- The first moment of the recording actually was black or blank. For example, the screen you were capturing was still loading, on a blank tab, or briefly went dark. Since Rekorder samples near the start, that's what ends up as the thumbnail.
- You recorded copy-protected video, such as a streaming service. Browsers block screen capture of that kind of content, so it appears as a black rectangle in the recording itself — and so in the thumbnail too. This isn't specific to Rekorder; it happens with any screen recorder.
- You recorded in Camera only mode with no working camera. If your camera was unavailable and you chose Continue anyway, the video shows a dark frame with the message "Camera unavailable" instead of your picture, and the thumbnail is taken from that. See Record just your camera, with no screen, Camera or microphone permission is blocked and Camera or microphone unavailable.
Why the thumbnail looks wrong
Because the thumbnail comes from a specific early frame rather than a summary of the whole video, it can land on a moment that doesn't represent the recording well — for instance a loading spinner, a tooltip, a browser dialog, or a mouse click. This is expected: Rekorder isn't picking the "best" frame from the whole video, only from near the start.
What you can do about it
- Wait for processing to finish. A recording still shows no thumbnail, or an old one, while it's processing. See It has been "processing" for a long time.
- Trim the opening in the editor. If the first second or two is blank, black, or otherwise not representative, cut it out and use Apply & render — the thumbnail is regenerated from the new start of the video. See Cut out a mistake, and reorder what is left.
- Start recording from real content next time. Give a page a moment to load, or wait until your camera has picked up your picture, before you start recording — the countdown gives you time for this, since nothing is captured while it's running. See The countdown before recording starts.
Troubleshooting
- The card shows a plain camera icon instead of an image. That's not a black thumbnail — it means no thumbnail file exists yet, usually because the recording is still processing or thumbnail generation failed. Give it a few minutes and reload the Library.
- The thumbnail in a share email looks wrong or generic. Share emails embed the same thumbnail, converted to a different image format. If no thumbnail exists yet, the email falls back to the Rekorder logo instead.
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