Pilot DAR has been talking about the subject of flutter which he understands.
This is what control surface flutter can look like on a Commanche.
TwinCom.mp4 video by johnfarley - Photobucket
I would guess the IAS here was about 150 max. Aerodynamic forces are dependant on IAS squared.
So the forces at 150 kt are related to 22,500 and those at 500 kt are related to 250,000 namely over 10 times as much.
The only way to stop such an oscillation is to slow down a lot. That takes time and may not be possible before structural failure.
I have lost several good friends during flutter clearance testing. The level of vibration with flutter is quite unimaginable unless you have experienced it.
It could easily dislodge a tailwheel from the up position.