Is there a way to allow a video file to be moved, but not allowed to be duplicated or copied? How is this done? For example, if I had a video file on a usb thumbdrive for a client, but I don't want him to copy and distribute it. Cut and pasting it to another drive is ok as long as it's moved without duplicating it?

No.

Andrew

Well you could encrypt it but then nobody could view it. Fundamentally if you can see it on a computer you can get hold of it on a computer.

I right click on the file, properties/security/edit, then deny full control except "read." This prevents copying and altering the file. However, I can't move the file around, which is what I wanted to do. For now, I can put a file onto a flashdrive, then lock it with the steps above. Client would then have to insert the flashdrive to their device and play it only from the flashdrive.

Anyone can copy the flash drive contents to other media. Those attributes are easily changed on writable media. As for using javascript on web interfaces it's easy to examine the code and determine where the file is and download it.

In general, rather than try to prevent copying it's better to eliminate the motivation for doing so and that's usually related to a change in the underlying business model. E.g. make compensation a attribute of the service rather than the end product.

Streaming might be an option but you're probably better off using a third party provider rather than trying to roll your own.

+1 for what Jim said - if you can read it you can copy it. All it takes to copy something is read, write, read, write,...

Something that I have never tried but in theory "Might" work on a DVD! At the end of a video sequence, include say 15 min of "Black" When you make the DVD put a small scratch on the outermost part of the recorded data, where the "Black" is! If you then try to copy it the software reading will report that it can`t read all the data & will therefore refuse to copy it, however, the DVD will still play in the normal way!
Thoughts anyone?

Now that is a great idea! Only copiers and complete file readers would get annoyed, and it would as you say play in an ordinary player. Clever!

Well, block by block read/write would still copy it. And the OP was referring to a Thumb drive as opposed to a DVD.

Regardless, short of encryption, there's no way to prevent someone who badly enough wants to copy something from doing so.