How do you watch offline video on a Nexus tablet?

My wife and I are considering a tablet for Christmas. We am considering whether to buy a Nexus tablet or an iPad for my wife this Christmas. We prefer the 7" size but there is no way we are buying the iPad mini with its 2 year old hardware for $329 so we are comparing the two Nexus tablets to the iPad 4.

Our most important use case is offline video play back for our kids. The key features that we care looking for in the tablet/video ecosystem are: offline playback, and somewhat ubiquitous cross platform service. iTunes is out because it only works with iOS and OS X (we aren't counting on a metro app for windows 8), as is Google Play (only on Android). The iPad, and our LCD TV, can both play Amazon instant Video and the iPad can download content for offline viewing. I really love android and would love to get the cheaper Nexus 10 and/or the better sized 7". However, we haven't found a good offline video solution for android. We have a couple of very long car trips through places with no LTE/3G so even if we were interested in paying for yet another data plan, the tablet has to be able to play the content without a connection.

We aren't getting a kindle fire because we have other, non-entertainment, uses in mind and we want to stay in the "pure" android ecosystem. Any suggestions would be appreciated.