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i want to know how can we prevent others to download the videos in my site. My site has the option of video uploading (in flv or mp4 format. Admin will upload them) and users can view the course videos online (using flowplayer) once they pay some amount.
But what i observed is that the users can download those videos using tools like Freecorder. I dont want this to happen, because videos have restrictive access and only for a particular period of time (till the user's membership expires).
So how can i prevent the user from being able to download the videos in my site ?
The fundamental law of video distribution is very similar to the fundamental law of software licensing. It goes something like this: Once you put your video on a screen you don't control, you don't have control over distribution of your video any more.
Even if you could stop them from downloading the file, you can't stop them from hooking a VCR to their video card and re-recording it. Even if you use some protected-path technology to stop that, you can't stop them from pointing a camcorder at the screen.
If you want to keep your videos under wraps, you need to show them in a theater under your control on screens you control, and have someone watching the audience for video recording equipment. Nothing else is going to have more than a very slight slowing effect on re-distribution.
This post is old but what I have done to prevent some types of copying is store the movies in a database and add an expiration and a username and password to the page that send them to the screen.
This will not prevent direct recording of the screen, but it is one more step to help.
Streaming Video Files If you want any real level of protection you need to use a true streaming server. The big advantage here is that the file is not actually downloaded to the user's computer—it is seen only as a real-time stream and there is no file left on the user's hard drive.
Streaming video provides fairly good protection. It will stop most casual thieves dead—only those with determination and a bit of technical understanding will continue to try and steal the video.
The most common method of stealing streaming video is to use a video stream capture tool. This is an application that captures a video stream and saves it as a file. This type of theft is extremely difficult to guard against. Although there may be some defences, e.g. denying access to known capture utilities, this level of defence starts to become a losing battle. A thief who is dedicated enough to use a stream capture utility is probably dedicated enough to do whatever it takes to get the video.
Even if the thief can't capture the stream directly, they can always use a screen capture utility. This is an application that captures whatever is displayed on screen. They can define a certain area or window (i.e. the video screen), play the video and tell the utility to capture it. There really isn't much you can do to fight this, but even if you could...
Anyone can set up a video camera and point it at a computer monitor. Anyone with a few clues can remove flicker and get a reasonable result. There is absolutely no way you can stop them from doing this. Although it's a very uncommon way to steal video, it's a good illustration of the fact that thieves always have one more option than the webmaster.
来源：https://stackoverflow.com/questions/4582433/prevent-video-downloading