Ok I have not posted in a while but I have some more time. Okay I have a few iOS apps to talk about:
Flixster is a nice app for streaming content (UltraViolet) to your iOS or MAC device. It does have some draw backs, it can't support Apple TV devices directly, the flixster service can be painfully slow since it must be streamed over wifi (unless you have a large cell data plan, and the app warns you as well). the app does support AirPlay but not in full screen mode (this is how you can send your ultraviolet content to Apple TV or a big screen TV). Video will not stream automatically without turning on mirroring to the device (and yes Apple hides this in option iOS). The support from Flixster is less than good.
VUDU Player is another media streaming app for iOS and MAC (ultraviolet content) I like the user interface much better than Flixster. It also can't interface with Apple TV since UltraViolet and apple can't seem to work out terms. It also supports AirPlay and AirPlay Mirroring (same issues as Flixster). the support from VUDU is much better overall. If you are purchasing DVD's/BluRay with digital copies most are moving to UltraViolet instead of iTunes so you will have issues with your iOS devices. Since I travel a ton I like to have a couple of video's loaded for long plane flights. FYI GoGo (wifi in the sky most us air carriers) does not support video streaming while in flight..
oh yes both apps will allow you to download your content to your iOS device ahead of time. Most movies start at about 1.2 gig and go up from there. Flixster does not support HD format either.