None of the factions other than the Saka Rauka and the Pahlava have real trailers, so you're not missing much. It's more likely that you put -nm on the end of the shortcut, or the "Turn off movies" checkbox in the EB configuration has a checkmark. If so, head to your shortcuts in the start menu and click on configuration. Get rid of that, and you'll probably be able to see the trailers.