It may seem counter-intuitive, but I find that photographs are much better at provoking emotion than videos on subjects where both are options. I give the nod to movies, documentaries and other interesting story-telling segments, such as you might find on YouTube or Facebook. America's Funniest Videos wouldn't be nearly as entertaining as America's Funniest Pictures...
I have thought many times about shooting video rather than photos. Both of my cameras can record HD and 3D video, in fact. But as I move through the Internet, I'm often moved by pictures far more than by other media.
Some of the most famous, iconic photography in history- the Hindenburg burning, Half Dome at Yosemite, workers on a skyscraper girder,the bodies from the Holocaust, etc.- would not be as iconic as video. Video is spoon-fed to viewers, always making them focus on the movement and thinking about what the videographer intends. Photographs give a viewer time to think, time to explore the picture, time to remember similar sights, time to see what they can see.
The Hindenburg disaster is a perfect example. The film is horrific, but it goes from the beginning to end while one watches the dirigible go up in flames. But once over, you have but a few seconds to feel sadness or horror, or whatever one might experience. Then you move on.
However, one may look at a photograph for several minutes, or longer, conjuring one's own story or memories, experiences from the past, or pure awe. It takes time for this to happen and photography allows one the time.
There are exceptions. I remember several distinct videos over the years. One was from 1978 when Karl Walenda fell to his death on camera while he was crossing a high wire between two skyscrapers in Puerto Rico. Another was when a reporter, stopped at a checkpoint in Nicaragua and being filmed by his crew, was kicked in the side and then shot in the head while prone on the ground. One more that comes to mind was watching live as the second jet hit the World Trade Center.
Photos, though, are able to reach your mind like no other medium.