Encrypt and Decrypt Data with C#

You can't easily encrypt and decrypt videos. The issue you have is that the players are a black box, you'd need to write your own DirectX filter that does the decrypting and require that people use it to watch your videos.

If you're asking for videos to tell you how to encrypt and decrypt data, I'd suggest you can never be a programmer if you can't read. There's tons of articles on the web for you.

If you don't mean either of those two things, then try making sense if you want help from us.