You can make "preview videos" that have a screen with a URL that people can type into their web browser to sign up and download the full version, but there is no video format that supports partially encrypted streams.
So, to do it, you would need to write a codec that would allow this, which people would have to install to watch the preview, as well as a whole DRM infrastructure. And most people wouldn't install the codec for the preview, and the pirates would just pull out the rest of the video stream and watch it/upload it somewhere.
4Nobody is going to buy and install a codec to watch one video. – Phoshi – 2010-11-10T23:01:35.880
Do not ever underestimate anything brother. Anyways, thanks for sharing your belief, but i will still try. – Anil Dewani – 2010-11-11T17:27:14.650