iTunes 10.6 lets you specify a preference for 1080p high definition video content from anything downloaded through the iTunes Store. The default video setting prefers 720p though, here is how to change that to true 1080p (Full HD).
- Open iTunes and pull down the iTunes menu to “Preferences”
- Click on the “Store” tab
- Click the submenu next to “When downloading high definition videos, prefer:” and set to “1080p”
- Close out of iTunes Preferences