How do you create Apache directives inside a .htaccess file that forces .mp4 and .pdf to download? Presently they seem inside the browser window. Rather, I'd like a download file dialog box to look.

Add the next into an .htaccess file:

<Files *.mp4>
  ForceType application/octet-stream
  Header set Content-Disposition attachment
</Files>
<Files *.pdf>
  ForceType application/octet-stream
  Header set Content-Disposition attachment
</Files>