Google launched universal search in 2007 and changed the world forever. How? Well, basically they started mixing in non-link content from a variety of sites. This content included videos, images, maps, shopping products, and beyond.
"It makes sense for marketers to increase the volume of video and image content they’re creating and to optimize it both on their own sites and on third party sites such as YouTube and Flickr." Dr. Horst Joepen, CEO of Searchmetrics.
Read more here:
http://searchenginewatch.com/article/2099640/Universal-Search-Which-Formats-Dominate-in-Googles-Results-Study