I have a better and faster solution I think
(anyway, the one I chose to do this kind of objects)
this solution uses the "spiral" tool. ("propeller" ? it is a google translation)
so, do a spiral, add a thickness to your spiral, and after, duplicate it and move it, and dupicate it and move it, ...etc (7 times to have the same result as your tutorial).
The only problem is that I can't smooth between two spiral.
(forgive my poor english...)