It actually is in the case I'm talking about. I'm talking about illegal websites where the only money generated is by advertisements on human eyeballs. They go way out of their way to make sure no scrapers/robots can see the videos on the page since it costs them money for bandwidth. In addition to referrer checking and captcha, they also have inline javascript that evals itself to un-obfuscate itself and load the video on the page so that if someone somehow beats the first two methods and loads it by a command line interface, they still don't get the URL to the video.