Hi archphotonyc,
Welcome to the Support Communities!
The article below may be able to help you with this.
Click on the link to see more details and screenshots.
iTunes: Sync purchased HD videos to iPod or iOS device
http://support.apple.com/kb/TS4223
1 Currently 1080p content is compatible with iPad (3rd generation), Apple TV (3rd generation), and a Mac or PC.
2 Some movies may not be available from iTunes in the Cloud. Learn more about where iTunes in the Cloud is available.
Notes: Your computer must meet the minimum system requirements for proper playback of 1080p content.
For movies which are available from iTunes in the Cloud, purchasing the movie will download the HD version to sync to your compatible iOS devices. When you purchase movies in HD that are not currently available for iTunes in the Cloud, the movies will download both the HD and SD versions to sync to your compatible iPod and iOS devices. Previous purchases may be unavailable if they are no longer in the iTunes Store, App Store, or iBooks Store. Some previously purchased movies are not available for iTunes in the Cloud.
Download previously purchased content in a lower resolution
The easiest way to put purchased videos onto your device is to download the videos from iTunes in the Cloud. This should make sure that you get the highest resolution video optimized for your specific device. Learn more about downloading from iTunes in the Cloud.
I hope this information helps ....
Happy Holidays!
- Judy