By typing =rand (200, 99) and pressing enter in Microsoft word ,it creates a random words up-to 407,000 .
To do this your mobiles file manager should have a option called ' create a file ' else download file manager called EsFile manager . First add videos and photos which has to be hidden in a folder and click add icon and choose create a file option and name it as .nomedia and press save . That's it now the photos and videos in that specific folder will hidden in gallery and in media players .