Locating a Specific Window in QuickTime and Exporting Contents

I am new to Applescript and still learning the framework so I apologize if this is a simple question.

I want to write a script that:

  1. Passes a URL to Quicktime
  2. Sets the window that opens to a variable
  3. Sets the volume of that window to zero
  4. Exports the loaded contents to an AU file

The code shell, I suppose, would look like this:

Tell Application “QuickTime Player”
getURL “http:blah.blah.blah”

End Tell

Can anyone kindly walk me through this process?