You can hide videos, images, notes and contacts in your Windows Phone if it runs on Windows Phone 8.1 version. Secret folder, Protect your files are some of the free apps which are available in the store and you can download it without paying a single penny. Another method to hide videos is by changing the video format. It is more easier than the first one. You can perform this method with the help of a file manager which allows to edit names of the folders. In this method just choose the video files you want to hide, click on the change name and remove the video format (for example if the file name is example.mp4 change it to example), then click save.