Database Server security settings > Security connections and progressive downloads
 
Security connections and progressive downloads
FileMaker Server supports progressive downloading of audio, video, or PDF files stored in an interactive container field.
Note  For information about interactive container fields, see FileMaker Pro Help.
When the FileMaker Server setting Use SSL for database connections is selected:
FileMaker clients download interactive content over an HTTPS connection if the server has a signed SSL certificate.
When the FileMaker Server setting Use SSL for database connections is not selected:
FileMaker clients download interactive content over an unencrypted HTTP connection, not an HTTPS connection.
FileMaker clients see the interactive data with little delay.
Notes
To enable this setting, the server should have a valid digital certificate installed. FileMaker Server provides a standard SSL certificate signed by FileMaker, Inc. that does not verify the server name. The FileMaker default certificate is intended only for test purposes. A custom SSL certificate is required for production use.
If you change the Use SSL for database connections setting, you must stop and restart the Database Server for the change to take effect.
Related topics 
Securing your data