How to force download with Amazon S3

I'm using amazon s3 to offer users large file downloads to save on
bandwidth. I've found the file with the s3 object and can send the url
to access the file, but I want to force the download instead of pulling
it up in the browser. These are large video files (.mov). Is there a
better way to do this?

I know that in a normal situation you would set the response.headers,
but I'm not sure how to do this with a file that is already on the
storage service.