David King, the Product Manager of Google's YouTube just launched this beta.
The idea is you can identify your works on YouTube and i guess others can know it is identified as being from you.
I'm not sure whether it's really for security rather then simple identification - the idea of being able to know what videos have been published - perhaps even by others - on YouTube by a simple hash query over the video content is quite interesting.
Jeramiah has some interesting comments on it.
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