Hi there! I see you’re running into the "this video cannot be loaded" error in the Secret Photo Vault app on your iPhone with iOS 18.6, and you mentioned permissions are set correctly. Let’s work through this together.

First, just to clarify:
- Are you able to open photos without any issue in the app?
- Is this happening with all videos or just specific ones?
- Have you recently updated the app or your iOS?
- Have you tried restarting your iPhone since the problem started?

These details will help pinpoint the cause.

In the meantime, here’s a step-by-step approach to troubleshoot this issue:

1. Restart the app and your iPhone
Sometimes, a simple restart clears temporary glitches. Close the Secret Photo Vault app completely (swipe it away from the app switcher), then restart your iPhone and try again.

2. Check video file format and size
Confirm if the videos you’re trying to open are in a supported format—commonly .mp4 or .mov on iOS. Unsupported formats or very large files might cause loading errors.

3. Confirm app permissions
Even if permissions seem right, it’s good to double-check: Go to Settings > Secret Photo Vault > Photos and make sure the app has "All Photos" access, not just "Selected Photos."

4. Check app storage and cache
Low storage on your iPhone or cache issues can sometimes cause playback problems. Verify you have enough free storage in Settings > General > iPhone Storage. You can also try clearing the app cache if that option is available within Secret Photo Vault settings.

5. Update the app and iOS
Make sure both your iOS (18.6) and Secret Photo Vault app are updated to the latest versions. Outdated versions might cause compatibility issues.

6. Try exporting or sharing the video
If possible, try to export or share the video out of the app to your iPhone’s native Photos app and try playing it there. This can help test whether the issue is with the video file or the app itself.

If you’ve tried these steps and the issue persists, please let me know which videos are affected and any other patterns you notice. That will help me assist you further.

Are you satisfied with this initial troubleshooting, or would you like me to guide you through advanced steps?