The Ewenki people have a rich history dating back over 3,000 years. Today, this history is often romanticized in the name of tourism, and many of the youth have left the old way of life and have joined modern society. These ethnic minority tribes have special cultural status in China.

They never ate their domestic reindeer, but they did hunt them for sustenance (and the few still living the traditional lives may still do this). The domesticated deer are used for milk, but they don't keep them fully penned in. The reindeer were permitted to freely roam, for the most part. Their breeding occurred naturally, as well.

Like many old cultures, they aren't all sunshine and roses. The people did cut off the “velvet” on their antlers prematurely with for Chinese without the benefit of anaesthetic. This is when the "velvet" is rich with blood flow, which isn't pleasant.

What this video shows is more about tourism, but the reindeer themselves are this friendly and habituated to humans. It's one of the few places on earth you can see this behavior and get this close to them.

Here is a thorough, (mostly) accurate, but slightly generous article written by China Today that talks about the Ewenki people.