How can I stream my screen to other computers?
Look at Desktop Sharing and/or the Remina Remote Desktop Client. Those were working for me under 12.04.
In late Ubuntu releases (like 14.04), Desktop Sharing was removed from System Settings, but you can still find and use it, and it's provided by the 'Vino' package, installed with sudo apt-get install vino. To setup the package run the vino-preferences command.