Free documentaries - many from sources like National Geographic. You can 'snag' the video and embed it in another site or a blog. This would be an advantage to engaging students outside the classroom.
"Where to watch free movies on the web? Here's a list that will get you started. We've listed 25 sites that feature a wide range of films. Classics, international, film noir, documentaries, indies - they're all here, waiting to be watched"