Same rules as photos, three extra traps
Hiding a video with the built-in Hidden album, a locked note, or a vault app follows exactly the logic of hiding photos — read the photo guide for the full comparison. Videos then add three traps of their own: they are big, they have thumbnails, and they need playback.
Trap 1: size
A minute of 4K video is hundreds of megabytes. Apps that casually re-encode, duplicate, or upload video will burn storage, battery and time — and an app that uploads your video "for processing" has already answered the privacy question. On-device chunked encryption is the only approach that scales to real videos without shipping your content anywhere.
Trap 2: thumbnails and previews
Every gallery shows poster frames. The question is where those frames live. If a vault stores thumbnails unencrypted for speed, the "hidden" video has a visible face — in app caches, in Spotlight previews, or in the system’s snapshot of the app when you switch away. A vault built for videos encrypts thumbnails with the content and blanks its own app-switcher snapshot.
Trap 3: playback leftovers
The lazy way to play an encrypted video is to decrypt it to a temporary file and hand it to the system player. That temp file is a plaintext copy of your secret, sitting in storage until something overwrites it. The correct way is streaming decryption in memory. You cannot see this from the outside, which is why vendor documentation (or an audit) matters more for video than for anything else a vault does.
Doing it properly
Record sensitive video inside the vault app when you can, so the camera roll never holds it. When importing existing videos: import, verify they play inside the vault, delete from Photos, clear Recently Deleted, and remember any device that synced in the meantime.