I’d been wondering about this. My bandwidth is somewhat limited: I have a 50 GB per month limit on my satellite internet, and my DSL is only 2 Mbps. So I had switched iTunes to download 720p movies instead of 1080p. (You can do this in iTunes > Preferences > Store.)
But I saw today that the iTunes Store has the the extended versions of the Lord of the Rings trilogy in HD for only $30. I don’t have them on disc; I used to have the Blu-Rays, but gave them to my son.
I wanted to buy them, and was curious to see how much difference there is between the two different qualities. Here’s the 720p version:
And here’s the 1080p version:
A difference of 1.4 GB; or about 5% more to get the 1080p versions instead of the 720p versions. And that affects not only your download size, but also the amount of storage you need.
I used to recommend to people to get the 720p versions if they’re strapped for bandwidth or storage; now, it seems like it’s a moot point. I haven’t looked at a lot of movies, but started noticing this recently with other movies I’d bought or rented.
Update: I’ve found out why there is less of a difference. As Ars Technica explained two years ago – wow, it’s been that long? – Apple is using better H.264 compression, meaning that these videos are only compatible with the 2nd generation Apple TV, the iPhone 4, or iPad 2, or later. If you have an older device, you’ll need to grab SD versions. The Ars Technica article says that the 720p videos are compatible with older devices, but the Apple article I link to above says that HD videos are not compatible. I don’t have any older devices to check; of anyone does, feel free to post in the comments to say whether or not the 720p videos will sync.
I only remember noticing the difference in the past few months, but that’s probably because I have a bandwidth cap on my satellite internet; before, I didn’t care.