Winrar [ You can Download from Here]
 Command prompt
 File (eg. vid.mp4) [Which you want to Hide]
 One image (eg. img.jpg)
Step 2 : Make one Folder in any Drive. For this example I am creating folder "errorcode" in "D" drive.
Step 3 : Copy your Image and file in that folder. Here I am copying "vid.mp4" and "img.jpg" in "errorcode" folder.
Step 4 : Select your both file ["vid.mp4" + "img.jpg"]. Right click on it. Click on Add to Archive and click on OK.
>>> Now you will see Three File in that Folder.
Step 5 : Now Just open your command prompt [strat >> run >> type "cmd" >> hit Enter]
Step 6 : Type "cd /d D:" >> Enter
Step 7 : Type "cd errorcode" >> Enter
Step 8 : Type "copy /b img.jpg + errorcode.rar newimg.jpg" [Note : Here you have to write your file name]
>>> Then you will see one Image file name with "newimg.jpg"
>>> Thats it..!!
>>> When you want to open your file "vid.mp4" then you have to just open your newimg.jpg in winrar.
>>> In winrar you can see your File.