Don’t take that headline to mean that you have carte blanche to purloin, take or willy-nilly start putting stuff on your site or in your corporate communications. Whoever took that picture or made that video owns the rights to it, and there’s a huge difference between you sharing it with friends or in your social feed and putting it on a corporate website, in a publication or in other kinds of correspondence (like newsletters).
TWO WAYS TO DO IT: BUY IT OR LICENSE IT.
BUYING IT:
There are any number of services out there from whom you can purchase an image. Creators (we’ll use that as the generic term for someone who has taken a picture, made a video or otherwise owns the rights to the material) may place these items in one or more places for “sale”, and that sale is a license by virtue of your contract of usage with the site offering that content.
A short list includes places like Depositphoto, iStockphoto, Shutterstock and Getty Images. Some sites charge a flat fee based on your having a subscription with them, while others may charge a varying number of credits (you buy blocks of credits) and others may charge based on your intended usage (in print, online, on television; wherever). It has been my experience that the most expensive is Getty Images, but they also have unique images that other more generic sites with staged images may not.
Some of those pictures and video also may come with a restriction on their use. Some cannot be used above the fold of a home page, others are for editorial use only (such as a news outlet) and not for commercial purposes. It is important to read the restrictions, if any, that govern the use.
LICENSE IT: CREATIVE COMMONS
Creative Commons is a platform that was designed to allow creators to license their images for multiple purposes, and the creator sets the terms of the license. 
Images and video that are Creative Commons licensed can range from not allowing the manipulation (or changing) of the content all the way up to it being allowed to develop entirely new and different content. Underpinning the entire experience, though, is the proper attribution of the content. Creative Commons works are free to use as long as you give credit.
HOSTING COMPANIES CAN BE FORCED TO TAKE DOWN SITES WITH ILLEGAL CONTENT
Ever gone looking for a video on YouTube only to find it was pulled because of a copyright claim by the rights holder? Copyright law carries with it stiff penalties for violations and companies will err on the side of caution and take down a site that may have unlicensed material rather than risk a legal challenge.
In the end, there are many ways to legally use pictures and videos on your website without resorting to a Google Images search and nicking it from somewhere. Use a photo or video subscription service and Creative Commons to insure your maximum compliance with your obligations and to protect the rights of the creators.