Found this on another forum. It's TV shows and not movies, but if it's just a distraction for on the plane or something it might be enough. I haven't tried it yet. I think it takes installing some reader or converter on the BB. Then you download the video to you computer and copy it to the BB using BB Desktop. videos4blackberry.info | Dig The Monday Line Up Folks.. | Blackberry, Click, Download, Full, Episode
Edit: Hm they're .3gp format so maybe can just be copied to the sd card.