Setting headers in sent_file response

I'm having trouble playing a video from my site on the iphone using
send_file. It seems that I'm missing the Accept-Ranges header in my
response. How can I set the Accept-Ranges header in my send_file
response?

I actually was able to edit the source of rails to get this
implemented:

vendor/rails/actionpack/lib/action_controller/streaming.rb

  def send_file_headers!(options)
        options.update(DEFAULT_SEND_FILE_OPTIONS.merge(options))
        [:length, :type, :disposition].each do |arg|
          raise ArgumentError, ":#{arg} option required" if
options[arg].nil?
        end

        disposition = options[:disposition].dup || 'attachment'

        disposition <<= %(; filename="#{options[:filename]}") if
options[:filename]

        headers.update(
          'Content-Length' => options[:length],
          'Content-Type' => options[:type].to_s.strip, #
fixes a problem with extra '\r' with some browsers
          'Content-Disposition' => disposition,
          'Content-Transfer-Encoding' => 'binary'
        )

        headers.update('Accept-Ranges' => options['Accept-Ranges']) if
options['Accept-Ranges']

        # Fix a problem with IE 6.0 on opening downloaded files:
        # If Cache-Control: no-cache is set (which Rails does by
default),
        # IE removes the file it just downloaded from its cache
immediately
        # after it displays the "open/save" dialog, which means that
if you
        # hit "open" the file isn't there anymore when the application
that
        # is called for handling the download is run, so let's
workaround that
        headers['Cache-Control'] = 'private' if headers['Cache-
Control'] == 'no-cache'
      end

And I send my file like this:

send_file path, :disposition => 'inline', :type => m_type, 'Accept-
Ranges' => 'bytes'

In retrospect this was dumb because mongrel doesn't even support byte-
range requests....