If I had my way we wouldn't have copyright at all. It seems idiotic to me for the same reasons patents are.
But we do, and so just as you say there are "legitimate reasons" why someone may wish to save a video, there are too "legitimate reasons" someone may want to share their work in a protected manner. It's a product. If you don't like it don't buy it.
There is no part of this that forces the user to view only DRM protected websites. As far as I can tell this only increases the rights of copyright holders, which, again, I think is stupid, but seems completely legal and a reasonable thing to do under our existing legal framework. Edit: it also does not seem like it will fundamentally change the user experience of the web since the things that it allows are mostly already doable, just not with an HTML standard.