Imagine being aboard this plane!

[Growler]

Originally Posted by Schroeder

I actually don't know what could cause such oscillations other than inexperienced flight students (pilot induced oscillation...not that that has ever happened to me when I was new to glider flying) or a completely screwed up loading of the plane (or maybe screwed up fly by wire controls ).

Pretty decent wiki article on what's called Dutch Roll, including ways in which such an effect is initiated. Looks like perhaps in this case there's some control inputs that aren't being registered correctly/at all.