I hate to sound like another "Nick Lappos fan", since I work for another company and spend most of my time trying to argue against him behind the scenes....
But- why must everyone argue with his discussion on VRS? What he is putting out is as close to gospel as it gets.
I can verify that what he is trying to teach us is the same information that is taught at the US Naval test pilot school (where there are just a few people knowledgeable in helicopter aerodynamics). His information is backed up by flight test data by BHTI and Boeing as well as Sikorsky. Recent flight testing on VRS has focused on the V-22 and its somewhat unique issues because of the potential effects of VRS on only one of the two prop rotors, but the V-22 data agrees with what Nick is teaching.
The arguments are entertaining, but don't confuse "my instructor says" with actual flight test data backed by aerodynamics lab work (wind tunnels, CFD, and other simulation.)
On the other hand, the arguing does help, because it prompts Nick to give his lessons again, which is a valuable refresher training...