vnc_auto.html was originally intended to show the minimal page/code that you needed in order to have a functioning client. Better naming that would have reflected my original intentions better would be vnc_minimal.html and vnc_ui.html. Additionally, it was always my intention that integrators would create a custom landing page based on some combination of vnc.html and vnc_auto.html (i.e. what Luke did). In regards to your specific question, if you add autoconnect=true as a query parameter to vnc.html (along with your connection settings), then it should connect immediately. E.g.
vnc.html?autoconnect=true&host=HOST&port=PORT&password=PASSWORD&encrypt=true
Regards,
Joel Martin (kanaka)