How to play mp4 using camera connection kit

The kit can only be used to copy photos and videos into the Photos app on the iPad. On iOS 4 (I haven't tried with iOS 5) I managed to copy an MP4 film via an SD card with the kit and been able to play it, but a film bought from iTunes didn't play (presumably iTunes bought films only play in the Videos app). Also the kit only recognises content that is in a particular format - the card has to have a DCIM directory off its root, with the photos/videos underneath it with filenames exactly 8 characters long (no spaces) plus file extension.

"a film bought from iTunes didn't play (presumably iTunes bought films only play in the Videos app)"

Yup, DRM videos can be only be played in Videos and nothing else (no 3rd party video players etc.).