Thank-you Svetoslav for the response. Previously we were directed to implement via the Properties/AssemblyInfo.cs. Is Global.asax now the preferred method? They should produce the same results I would expect.
I believe I have identified that this can/should work as I expected, and part of the cause may be a caching issue. It would seem that somehow the Sitefinity admin screens are forcing a no-cache solution when one clicks the [Open the file] button; our front-end is using the URL provided by the MediaContent object. It seems that the Admin screens append a querystring parameter (status=Temp...) which the MediaContent object does not provide and therefore our front end does not utilize. Is there any guidance on how we should utilize the querystring? is the status relevant to caching headers?