A free program for Android, by KGFMOB.

Our Phone Vault: Hide Photo Video app is the best way to hide photos and videos from your device. It has a simple and intuitive interface that will make it easy to hide your photos and videos, and you will not need to take any further steps. Once you have installed our app, all you need to do is select the files you want to hide, and then click on the “Move to vault” button. Our app will take care of the rest, and you will not need to do anything else.

Once you have hidden your photos and videos, you will be able to view them in a safe and private way.