Download the programme "Requiem". It removes the DRM from video files bought off of the iTunes store. It will not remove DRM from rentals though, as the programmer felt this would unfair as you didn't pay for it in full. Requiem uses quicktime to remove the drm, and does not convert it (ie lose video quality) instead it remakes the while file but without the drm. Oh, and it keeps all the metadata too!
it does not work with iTunes 11, so you will have to remove iTunes 11 completely - this means removing all iTunes related files in my computer even after you have uninstalled it. If you have issues with removing iTunes 11 follow some tutorials on youtube. Side note - when requiem is in use you cannot have iTunes open, also a HD tv file will take around 8 minutes to remove drm...you can follow the progress by locating where the original file is and refreshing the page which will show you how many MBs have been made, the original file will be the exact same size as the new file..whjch is awesome because there is no loss of quality.
ENJOY!