Looking at Fox News, the site has a specific section entitled "Video." There are a number of featured videos and a Mobile Video subheading as well. Most of these videos will just run one after the other, set up almost like Hulu or another site of the sort. There is generally much less writing or none at all, except maybe a line resembling a lead to give a little background. Many news stories will have pictures with captions and those stories tend to be a little shorter and occasionally reference the picture.
CBS is slightly more discreet about the mobile and radio options available, but they are there if you look hard enough. The "bigger" stories were more likely to have pictures or video involved. The video section of the site was down when I went on but videos would show up elsewhere.
Mobile options are great in this day and age because it seems like everyone has a smart phone or tablet device at hand. Audio seems to be dying, especially with how everything is going HD lately. Audio can still be great, especially for elections and such where you want to hear the intonation in someone's voice.
Video is obviously a good way to round things out as well because it tends to give a lot of good background and it's easier to feel the tone of a particular story. Photos do a nice job of advancing stories, in my opinion. It's nice to put a face to the name in a story or to get a better idea of the setting of a news story.