I saw this footage quite some time ago.
I think it was NASA or a similar agency used the PA 30 for flutter testing. This flutter was deliberately induced, I think the aircraft was taken to or just above Vne.
The PA 30 is a very strong airframe, this film is testament to how strong it is.
I remember hearing a story told of a pilot speaking at a Bonanza owners meeting telling of his escapades of cloud seeding experiments and airborne thunderstorm studies. When asked what model Bonanza he used he exclaimed that he never would never do it in a Bonanza, he did it in a PA 30.