You can require an additional security code to further protect your files. When this permission is set, recipients will need to enter the custom code before the media will open.
Step 1: Open the Share Panel for a file by clicking the 'Share' button in the media tile
Step 2: Once you have entered the recipient email address select 'Require Extra Security Code,' which you will find inside the box labeled, 'More.'
Step 3: Set a custom security code.
Step 4: Enter the Email Subject and Message fields and press 'Send.'