The Clipchamp API's "onPreviewAvailable" option lets you submit a preview/still image together with the user generated video. You can use such a preview image to display in your media library and/or on your website to show visitors what the video contains - similar to how YouTube and other video platforms display a still image as a placeholder for a video before it plays back.
"onPreviewAvailable" provides a callback function that we can call with the preview image, once it becomes available. Here is an example of how this works:
You will have to upload that file to the same (or optionally another) folder in your cloud storage, for instance a bucket in AWS S3. We do not currently support uploading it alongside the video on our end.