This is a very useful application called "Hide IT Pro" and it allows you to hide your photos and videos in your Android phone. It is free and after you install it, the application is actually named as "Audio Manager". Yeah, you know why it is renamed but it does really function like a Audio Manager as a secondary function. You can set the volume for your devices with this application and it really works.
However, the main purpose of this application is to hide your private data including your pictures, videos, music, application and SMS as well. I only tried videos and pictures. It works perfectly! For hiding application, you need to root your device which I don't intend to. If you have rooted your device, probably is a good try. You know sometimes we don't want others to see what application we have installed! :)
This is main screen and to enter to the real function of this application, you need to click and hold the "Audio Manager". It will ask you for password for first-time setup and after that you need to enter the password to enter. It is 4-words password. :) After you enter, you will see this vault folders.
So each folder contains those files that you hide. To hide, just go inside this folder and press the "+" sign at the upper right corner and start choosing files that you want to hide. After hiding, this file can only be viewed by this application. You can create your own folders in this vault as well for better files organization.
You can also unhide these files buy clicking and holding the picture or video for example. Then choose unhide. It will ask you which destination folder you want to unhide your file to or you can choose the default one. The good thing about this application is you don't need to unhide to view your pictures or videos. You can view directly with this application without unhide it! :)
Anyway, this application is very user friendly and you shouldn't have problems to use it. Let's try it out yourself here.
P/S: I am hoping to see an application that allows you to hide apps without rooting your device. It seems like is not technical feasible at this point in time. :)