unfinalized video repair
Why this video problem happens
A video is often finalized at the end of recording. That final step may write the duration, sample table, track relationships, metadata, and other information a player needs. If power fails or an app crashes before finalization, the file can be large but unreadable.
Most camera-style recordings are more than a stream of pictures. They also need a readable container, indexes, track metadata, timestamps, codec information, and audio/video relationships. If a recording is interrupted at the wrong moment, the actual media data can remain on disk while QuickTime, VLC, Photos, or another player reports the file as empty, zero seconds long, or unsupported.
That is why a broken video can look impossible even when the file size is large. A 1 GB recording that shows 00:00 is often not empty; it may simply be missing the instructions that tell playback software where the frames and audio packets live. Repair starts by treating the file as evidence, not as a normal playable movie.