Again, as others have explained, if it’s for news or editorial purposes, then there is no requirement for a release. Releases are generally only required for commercial use.
It’s worth noting, too, that the definition of “commercial” for these purposes is NOT simply that the photographer or the media outlet might make some money from it. Many photographers make money by selling their photos and videos to news outlets, as described pulykamell above. Many news organizations also make money from the images and videos they create or purchase, by selling their stories, and by running ads. But that’s not really what commercial use means in this context. The fact that a media outlet might be a for-profit business does, by itself, not constitute “commercial” use of a picture or video.
Commercial use in this context tends to mean advertising or promotional use associated with a particular product or service. But it’s not quite that narrow, either. If the subject of your photo can, through the way the image is used, be perceived as supporting or endorsing an idea or philosophy or specific organization (not just a product or service), then you have to be careful.
Take your example of a Trump supporter punching a protestor.
If you want to display that image in connection with a news story about the protest, or about the current state of politics, or about the predisposition of Trump supporters to violence, or any one of dozens of other possible news stories where the image is relevant, you would be fine without a release. If you wanted to use it to illustrate some commentary about the sad state of American political discourse, or about how Trump supporters are the only ones with courage, or whatever, that would be fine too. And those things would be fine even if you make money from your news or editorial articles.
But if you show the image with the caption, “Red Bull really packs a punch,” you’re going to need a release, because you’re directly associating the subject with a specific commercial enterprise, and implying some sort of connection or endorsement.
And if you use the image in a National Rifle Association poster, with the caption “Here’s how we defend our second amendment rights,” you’ll probably also need a release, even if you donate the picture to the NRA, and even if the NRA is a non-profit organization, because the use of the picture suggests a connection between the subject and a particular organization and set of ideas.
And as one of the links provided below notes, there are even cases where editorial use can lead to someone suing you if your use of their likeness does harm to their reputation. There are, at the margins, quite a lot of grey areas here. The borderline cases often come down to questions of newsworthiness, the public’s right to know, and whether the harm to reputation is greater than the informational value of using the image.
These links touch on some of the important issue:
http://artlawjournal.com/need-model-release/
http://www.pdnonline.com/features/What-Photographers-N-10515.shtml