A few things I was taught back then about ETL:
When landing, coming to a stop in the hover, ETL is lost under c.a. 25kts airspeed. The airflow over and under and all around changes and hits the helicopter from everywhere and everything starts to shake and shiver. The ****ty pilot thinks he is loosing control and makes a browny on his tail and overcontrols the heli when trying to stay out of the incoming shed!
Pretty good explanation... ei...?
Here's what actually happens: The shuddering is caused by the tail rotor going into turbulent air caused by the main rotor downwash as the heli slows down.