I’d like to chime in as well.
All this change does is make it more difficult for the people who weren’t going to break the rules in the first place. There are a multitude of ways to get the videos without the API. Via scraping, flv downloading, bot-caching, you name it. This is an example of bad DRM, something that pretty much every twitch broadcaster knows inside and out.
Heck, if you want to give broadcaster control over their videos, why not simply add a radio button right next to the “allow embedding” that says “allow downloading”, and let that determine if the download links will appear in the API?