If you are running on a Mac you can use Mac OS X's web sharing to stream videos from your Mac to any iOS device. This also works for protected content (i.e. iTunes Fairplay DRM) and since it is a pull-type technique you don't need to start the stream from your Mac, you just select from a content list on the iOS device and open the file for playback. Works from within Safari on the iOS device so you don't need to add any third-party utility to make it work, you only need to enable web sharing on the Mac and then create some UNIX links to the directories that contain the content.
Here is a write up on this technique, I've been using it for months and it works VERY well.
http://www.macobserver.com/tmo/answers/stream_videos_and_music_from_your_mac_to_your_iphone_or_ipad/