This was filmed at LDSB on Tuesday
The Grob 115 (UK military designation – Tutor) has an aileron/rudder linkage to help address adverse yaw.
Peter the video shows aileron to elevator linkage? Perhaps you need to change the thread title?
Not sure why there would be a linkage between aileron and elevator-perhaps it is due to a control lock on the ground?
As for friese ailerons or aileron/rudder linkage – none of this makes sense in a competition aerobatic aircraft. All design features used to reduce adverse yaw when upright will make adverse yaw inverted much worse.
Dave_Phillips wrote:
The Grob 115 (UK military designation – Tutor) has an aileron/rudder linkage to help address adverse yaw.
Mooneys also have such a spring connection for the same purpose.
[EDIT]
Oops, but I just realized, Robert is right, it appears to be an aileron elevator connection!
Peter the video shows aileron to elevator linkage? Perhaps you need to change the thread title?
Sorry – title fixed 
I seem to remember it being done on model aircraft but I’ve never heard of it in full size aircraft before.
Hopefully the person fiddling with the aircraft had permission from the owner.
Actually the controls were being moved around by wind, since the owner forgot to lock them
My guess is a seat belt around the stick.
Don’t think they’re linked. Could be parachute harness over the stick. That’s what I use as gust lock.
Imagine a vertical roll. Any movement of the elevator is instantly visible from the cabin as one wing moves under/over horizon and the plane leaves vertical rotation axis. Means penalty in competition.
