Both apps
When a video has sound, but no picture
Understand video compatibility without losing the original.
Check whether the file is still being written
Wait for an active download or recording to finish. An incomplete file can be useful for recovery but may not play in every application.
Try a compatible player
A container such as MP4 can hold different video codecs. QuickTime or an in-app player may not support every stream. If a file has sound but no picture, try VLC, downloaded from its official VideoLAN website.
Official VLC website ↗Keep the original
Do not delete or overwrite a file just because one player cannot display it. Make a copy before converting it. A compatibility conversion may take time and temporary disk space.
Tell us what happened
If playback still fails, send the app version, your operating system, file extension, player name and the exact error. Do not attach private recordings unless support explicitly arranges a safe, consented transfer.