One can't help but wonder if it has something to do with not operating the aircraft appropriately. Vne is not the only consideration. Not knowing or operating the aircraft appropriately with regard to the correct Va speed for the aircraft weight and altitude for example. That kind of flutter would not be considered normal for normal operation and certification purposes. Of course another consideration with an ageing aircraft is also slop in linkages/unbalanced control surfaces etc which would induce flutter at much lower speeds than normal. That second vid looks like someone wanted to start playing test pilot - good luck to him...!
