When logged in you can start the automatic player in the left menu. Actually theres nothing more to it, just keep the current window and the player windows open.
You can only view a video once from one location, this is bound to your IP. So if you are on a different location, you can watch the videos once more to earn more credits.
With the Free subscription you can run two players, with the Starter subscription four and with the Pro subscription you can run six players simultaneously.