Try running that from the command line, and you'll see it print your HTML after the redirection header lines. Whether or not the HTML will appear in a web browser will depend upon many things, among them:
- Is the browser picky about the absence of <head> and <body>?
- Does the browser bother to show the content if the redirection succeeds?
- Does the browser have time to render the content before the server that
receives the request from the redirect starts talking?
What it will not do for you, though, is present you with the option to do your download. The redirect is unconditional. If instead you want to present a hyperlink to the download URL, then just do that without bothering with a redirection header.