Why on earth is everyone asking for a tutorial. You are literally watching what he's doing haha! Just slow it down with the speed control and copy what he does.
There's no evident scientific basis for the close-up shape of that particular nebula. The 3D artist just confabulats what (s)he thinks may look nice for an animation. The result, while certainly looking pleasant, having an even greater emotional impact with dramatic music, is scientifically void of information.
