Update 25/01/2013 - fixed language bug
This is the free downloadable version of Real Preview for Joomla 2.5. There is no demo of this
Download and install the component and plugins as normal. Publish the two plugins.
The important bit is to make sure the Real Preview content plugin is processed before other site plugins. To do this you just filter your content plugins and set the order to a minus value like in the image below.
If you wish to stop using Real Preview simply uninstall to revert back to normal Joomla article editing.