DRM works great, but DRM is not for protecting content from piracy. It's for getting leverage over playback device manufacturers.

https://plus.google.com/+IanHickson/posts/iPmatxBYuj2

That's a very interesting point of view, thanks, it certainly makes sense. Though I don't really understand, why bother with all those encryptions, if you can just add some metadata to the video container. Something like "printing is forbidden" flag in PDF.

Usually metadata like "printing is forbidden" or "ad is unskippable" is effectively optional, as someone could write a player that ignores it.

However, adding any encryption covered by DMCA makes it the law, and allows you to use the police to enforce your file format's specification.