Once you transfer your content to the Secret Photo Vault app, to access these specific files in the future, you'll always have to enter your password. This means you want to make sure you set a password that you'll always remember or you'll never be able to access these files ever again.
The app can automatically synchronize with your gallery. Just select the option when you setup the app and whenever you take new photos or videos, they'll automatically be saved to the app's directory, and protected with the same password. Likewise, you can always delete any item you no longer want to store, or unprotect files if you don't care about people finding them.
With Social Photo Vault, you also have the option to organize the content into different albums and download them in the optimal quality so they take up the least amount of space on your device.