Stream from Mac to iPad

We've been told that in the newest version of the iOS, we can now stream music and video to an iPhone or iPad. But nobody could figure out how. And somehow Apple's helpful weekly newsletter explaining new functions got lost. (That's satire, Apple doesn't make such a thing.) But this page explains it. It's pretty kewl, I'm just watching Eat-Love-Pray on the iPad, even though it was bought and downloaded (HD, several gigabytes) to my Mac Pro.