I'll let you in a little secret somebody told me about called Requiem. It successfully removes the DRM from iTunes movies, but it will only work on titles that you bought. It won't work on rentals, etc. They had something similar for music before iTunes went to mostly DRM free music.
First step is you need to download iTunes 10.5.3. It's a little bit older version, but Requiem hasn't been updated for the latest versions of iTunes yet. A simple Google search will lead you to somewhere that you can get 10.5.3.
Next step is to make sure you have Java installed on your computer, or else go to their website and download it and install it on your computer.
Next step, go here. This is the link for Requiem. This is for PC, if you need the Mac one, the YouTube video has it posted in the link.
Lastly, open iTunes 10.5.3, browse to the part of the iTunes Store that says "Purchased," and you will need to re-download your purchased movies. Once that is done, close out iTunes, and run Requiem and it should successfully turn them into a DRM-free .m4v file.
Here is a YouTube video on it. This is the guy who told me about it so if you have any questions, I'm sure he can help answer them.