What is "aircraft stability" - IN VIDEO

[Crumpp]

Hurricane would not move to trim speed and stay there

Yes, a stable airplane will move to trim speed.

If it is statically stable it will move towards trim speed when disturbed.

If it is dynamically stable it will reduce the amount of speed it overshoots trim speed with every oscillation.

The oscillations will grow smaller with each cycle until they are dampened and disappear.

Just like what happens with the Spitfire's stability in Cliff's of Dover....