What is the white connector on the front of the Saber DA-1N1-I and the DA-1N1-E?  Do I have to connect it to something?

You do not have to connect it to anything.  The white connector can be used by system integrators to attach S-Video and Composite Video connectors to the front of the computer case.  If your computer case has connectors on the front, you can use the connector, otherwise, just ignore it.