How do I prevent my files from being copied/downloaded?

I’d like to share a QT movie of a Keynote (or PPT) presentation that’s viewable on my website, but I don’t want people to be able to copy or download the file. Is there a stack for that?

There are some stacks out there to protect content, but they all only work with text and/or images. I don’t think there is any way to protect Keynote or PowerPoint presentations, but you could hide and password-protect them for example with Joe Workmans “Page Safe” stack:
This way only people who know the password will be able to view (yes, and download) these files…

Nothing is safe on the web. If you display content on the web, someone will get it. Even the protecting of images only adds roadblocks. If someone is smart enough they can get it. If this is a video, I recommend that you upload it to Vimeo or Youtube. Vimeo does support private videos