This plugin will do a query on IMDB for movies on your harddisk and will show the info in a popup. For now it will always take the first result that comes back from IMDB.
The plugin is already available in the latest stable official images and should be available automatically.
If it is not installed yet, use the ipkg manager: SSH onto the dreambox and run
ipkg list|grep imdb ipkg install enigma2-plugin-extensions-imdb
After that, restart the Enigma2 GUI by either running "killall enigma2" or using the restart option from the dreambox menu.
Run it from the extension manager. It automatically searches for the currently watched movie.
An alternate way to launch it is pressing the "info" button for a longer time. The menu that shows up lists the IMDB plugin, too.