Pond 5 is without any question one of the best agencies to sell video footage. They are innovative and have an interesting earning system, where you can set the price for your work yourself. Every clip from HD to 4k will sell well and pay off nicely!
Why Shutterstock? Shutterstock is, without any question, the number 1 best selling agency for most independent microstock photographers and illustrators. I personally earn about 50% thanks to their website. The company was founded in 2003 by Oringer, who uploaded 30,000 of his own stock photos and made them available via subscription, forming the basis of the company.
The Microstock Guide 