RE: Flying wing gliding in high winds
I think you are still off base. In both cases you posted light airplanes flying in strong slope lift. The " Wind " is being directed upward by the slope and thus providing lift. In the first video the combination of lift and wind speed exceeded the gliders terminal speed because the wing loading was too light. Increasing the airplanes wing loading would yeald a higher mass. Mass= potential energy, pointing the nose down would convert potential energy into kinetic energy which means speed. If you went further with your serches you would find an R/C glider doing well over 400 mph ground speed on a slope site that has winds blowing 60 mph.