How do I as a content provider force WMP to download my ASF instead of streaming it?
There’s various ways of doing this. You can add “?mswmext=.com” to your URL (taking advantage of an undocumented/unsupported Feature of WMP’s progressive download code which is not supported past WMP7.1), use ASFCopy (from the Windows Media Rights Manager package) to add Content-Disposition headers (this would also be very for you to do in ASP or CGI), or use a Borders (.WMD) file (documented sparsely in the Windows Media Player SDK, documented better here) to install a package containing the ASF file(s).