In my previous post about Google Chrome I already described what you might need to do with your certificates to get connected to the console of a VM in a vApp.
Here you will find a step by step description for Firefox and Adobe Flash Player
Access your vCloud Director Portal:
Adobe Flash Player:
So here you need to configure Firefox to accept the Flash Plugin (enter about:config):
Create a Boolean entry:
Set to true:
After these steps, go ahead connecting to your console port proxy (8443 in my case):
If you see the white and empty browser window, everything is good. Go ahead with downloading and installing the Adobe Flash Player Plugin.
After restarting your browser you are finished: