First of all, the fact is that transferring huge files over HTTP is not going to work. And if you make it work, you've only done so by stretching an unsuitable technology to its brim and jumping through hoops. So, technically this is the wrong solution. Not much discussion regarding that, IMHO.

The question you're raising is different: "I need to transfer huge files online and I need to use a web interface for the client. What should I do?" in which case the answer is very simple. Write a method that returns right away but runs upload code in async that uses FTP or some other well-formed file uploading protocol." Very simple.

While clients should get what they want almost all the time, they don't understand the technology and since you do, you're in charge of making the correct usage of it. "No, I can't make your website shoot bubbles from any random user's floppy device".