I think the best way to help cut down on image / video theft is using a script proxy to serve up the images from a different server not on the "Cloud" but just on the internal network, protected by only allowing access from an internal IP on the Web Site server.
We call this dual homing, where you have one network adapter connected to the public internet "the Cloud" and another on the internal network. You can use a scripting language to stream video and images from the protected server to the client browser, no direct linking would be possible and the directory hosting the images and videos would only be accessible from the web site server or if someone was physically at the protected server.
This by no means is a 100% solution but it sure will cut back on the theft. Invisible water marking on images and in video would be useful now as they would have to scrape the videos and images which means they would get processed in a script before being displayed and would be watermarked.
Finding a good method to track them down would be an issue, but at least they would be traceable.
My,
