Re: Double Haul.... Won't.....
I have read all the thread. I agree that the whooshing sound on the Rafeff video is probably the sound of the rod cutting the air. Also, I agree that a Clouser might be a little heavy for a good distance cast on a 6wt. I think the weight of the eyes would tend to drop the loop and reduce efficiency.
I was coaching an experienced but not trained caster a couple of weeks ago who had the same haul/backcast problem - which I did myself somewhat when using his rod. Changing to a newer and heavier line solved the problem.
Be aware of two things: casting 7 more feet (ie 47 vs 40) is equivalent to casting a 40ft line of one weight heavier - so to see if you need a heavier line, test by seeing if the problem resolves somewhat by holding more line in the air. Secondly, some lines (Rio I think is one) are more like 1/2 wt heavier for their rating - i.e. marked 6wt but more like a 6.5wt. The product descriptions on company websites and a professional flyshop owner will help.
Plus, as others have mentioned, clean and lubricate the lines you do have after each outing or practice session - you will be amazed at the microscopic dirt that comes off in a cleaning cloth. Cheers: the Canadian Greg H. from Toronto.