@Driving Van Trailer: For clarity, did you add the video to the Secure Folder via the folder itself (Tap the 3 dots in the top right > Add files) or via the Gallery app > Select the video > More (3 dots) > Move to Secure Folder? The location of the video file in the Secure Folder will depend on where you moved it from. For instance, if you moved it from your Gallery then it should be visible in the Gallery app in the folder. If it was a download then it will be located in My Files > Downloads etc. For further information, please follow the link below.
https://www.samsung.com/uk/support/mobile-devices/what-is-the-secure-folder-and-how-do-i-use-it/
