>The security is about preventing other programs from being able to capture the video and audio. Sometimes programs want the ability to output something to the user, but don't want other programs to to be able to save it or analyze it.
The big gripe of a lot of people is that what this actually means is DRM, and that functionality is not there to offer security to the end user, rather to offer security from the end user.
At a philosophical level, when the end user purchases computing hardware, this traditionally has meant that the hardware became the end user's property, and it becomes the owner's intrinsic right to use it how they want, even to misuse it -- You wouldn't buy a car that was incapable of going 16 mph in a 15 mph zone, or making a turn without the turn signal being activated, would you?
Frankly, I even get the desire for piracy. Piracy is not theft, it does not strip another person of their property. You may argue that it strips the original content creator of their royalty (plus the parasitic organization publishing the content of their 95%+ "fee"), but I'd counter by suggesting that even of the pirates who could afford to pay for such content, ~99% would not otherwise pay for that content if they weren't pirating it, so that's really a false argument - if they even would pay for it, then they'd have just paid for it, wouldn't they? Not to mention that piracy democratizes access to diverse forms of art, making it available to the poor, who have just as much a human right to appreciate art as the rest of humanity. Further, the piracy ecosystem preserves otherwise lost forms of art. I wanted to watch a 1998 German movie called "23" a couple weeks ago. Couldn't find a legitimate copy available to purchase or stream anywhere in my country, neither physical media nor digital, but TPB had multiple copies with English subs.
Besides, it's not like these security coprocessors (including Microsoft Pluton, the private-sector newcomer to the probable public-sector "security coprocessor" club) actually prevent competent folks from capturing media. They're a nuisance that raises the cost of computing hardware, ostensibly a public good in the information age, while doing effectively nothing to prevent piracy.
If even a single argument for the legitimacy of the existence of Intel CSME and AMD ST is DRM, a.k.a. "to prevent poor people from appreciating art, ensuring that countless artistic creations are lost forever, and needlessly raising the cost of a utility that borders on a public good", I can only hope that I've demonstrated the downsides of this argument.