I have had to study this carefully and find that the typical helicopter undergoes about 2 to 3 g's of lateral vibration if an entire blade comes off. This occurs at about 3 to 8 cycles per second, a really bad ride. For most helos, this vibration magnitude and frequency takes the tail cone off, and the rest is history.
That film of the intermeshing Pumas taken on a home video shows the tail collapse on both machines, look at PUMA Helicopters Midair Collision half way down the page:
http://www.helisite.be/list_link.php?cat=9