I searched a while and find that, because the end user will always download the video content to local machine, it is impossible to protect the video content from stolen.
But as we can see, Youtube and Hulu have provided video pay-per-view system for quite a while. So how can I protect the content like them? Is that because they are using flash?
There is no way to protect video content. Only you can do is to make it harder to steal it. Whatever you do to protect, always is a way to steal it like capturing the monitor output. So don’t waste to much time/money. Best way is to protect is to copy right it.