Sectos is a free Android app to hide photos and videos, it is fairly easy to use. After launching the app you select the photos or albums you would like to hide and they will be moved, changing the file so that no app can recognize them as media. A camera mode will automatically hide any pictures you take right away without needing to manually hide them.
The app unlocking code is stored as MD5 hash and photos are secured with what the developer calls a “high-secure algorithm“. I would be wary of using Sectos to hide very sensitive pictures from a resourceful attacker due to lack of app information about what encryption they are using if any. It is impossible to evaluate what they call a high secure algorithm, more specific information is obviously needed to trust something marketed as a security product.
I liked from this app that it can hide its existence by removing Sectos logo from view and the app can be locked using a PIN or pattern. This stops noisy people from looking about after coming across a photo hiding app, which is very tempting to play with for one too many. Sectos PIN number prompt only becomes visible after dialling a preset number on the phone without that nobody should be aware it exists.
You can back you up your hidden data using the app integrated cloud storage services, Dropbox at the moment and Google Drive support planned for the future. Cloud back up can be set to automatic. If you forget the passcode, it can be reset via email link going to Settings > Privacy settings.