Probably going to confuse people more, but as far as I can tell, you have to make sure you know what the Digital Copy version is... basically DVDs/Blu-rays come with 2 types:
1) Ultraviolet - As per above, using Flixster, Vudu, etc. and linking to your Ultraviolet account (I actually use both), you can redeem the UV code on Flixter/Vudu's site after logging in. The movie is then immediately available on Flixter/Vudu's sites or if you have the Android App, via the app on your phone/tablet. Within those apps/sites, there is a link to download the local/offline movie if you won't have Internet access.
2) Digital Copy - These appear on the DVD/Bluray box as "Digital Copy" without a Ultraviolet symbol. From what I can tell, most of it depends on the Production company... from personal experience, no Disney/Pixar films are UV capable (you can't even perform a Vudu "disc-to-digital" conversion). I'm sure there are other companies that are also incompatible, but as I have a Daughter that loves Pixar movies, this is especially a problem for me since she has a tablet and I'd like to have it loaded with her movies.
From what I can tell, #2 above can be redeemed on your Windows (perhaps Mac) computer by putting the Disc into your DVD drive, entering the code and it creates a folder for your Digital Copy. As part of this process, it asks if you want to make an iTunes compatible version, or Windows Media version. I don't use iTunes, so I've always chosen WM. I saw somewhere that you can supposedly hook your Android device up to your PC and using Windows Media player, sync the Digital Movie to it, but I have not been successful in doing so, I think because (as someone above said) Android doesn't handle iTunes or WinMedia DRM.
In the past, using AnyDVD and CloneDVD, I've been able to rip a DRM-free copy of videos, converting into a .WMV file that I can then copy to Android device and use a media playing app. I have not used these programs in some time, but would suggest that they are worth the investment for purchasing your own licenses for them. In that manner, you can actually just rip the DVD (or if your PC has one) or Bluray disk and save to your PC's hard drive that way as I think ripping the digital copy files is a lesser resolution and audio quality (if that matters to you).