Basically by allowing websites to refuse to load unless the browser the operating system running the browser promises that the user isn't allowed to know what the computer is doing. And Google super duper promises this won't be used for evil.
YouTube doesn't have invasive DRM (on normal videos), playing any resolution works on Linux.
Netflix only ever plays in 720p for me however, regardless of browser (you can check the stats with crtl + alt + shift + d). There are extensions for Firefox and Chrome to fix this issue luckily.
But if Google's DRM for the web goes through this might not be so easy anymore.
allowing websites to refuse to load unless the browser the operating system running the browser promises that the user isn’t allowed to know what the computer is doing
That seems to be the message everyone is drawing from this.
I think it'll be more insidious than that, there will be Linux, but only "signed, verified" Linux will be allowed, and the only Linux distributions that will make that list are the ones with corporate or government versions. Specifically distributions like Google's Android, IBM's Red Hat, Canonical's Ubuntu, and China's Kylin.
This is still as horrible. Imagine Ubuntu winning the snap vs flatpack exchange, because their OS is 'legit', whereas every other distro is pushed out, because it's too much work to install an unsigned OS.