Thie video is partialy wrong. Wind turbines have alot of energie stored in the rotation of their blades. Wind rurbines are actully required to provide energie for the system in case of a frequency dropp. Furthermore alot of WT run on 90% efficiancy and go up to 100 when needed,(reply>), @Jan Correction: the relatively new ENTSO-E grid code Requirements for Generators (RfG) require all large wind farms to be operated below available capacity and provide power increase in under-frequency situations. This has already been adopted by National grid and TenneT in 2016 and probably by others since then.,(reply>), @đeri662 to my knowledge these kind of requirements apply atleast for all of europe. And with 90% i mean 90% of there theoretical maximum i.e. if they could extract 40% of the winds energy they run on 36%.  The cool thing is: this can be achieved by overspeeding the rotor above the maximum power point. When the turbine slows down you get more power from the rise in efficiency and from the rotational energy of the blade,(reply>), Where are they required to do so? The efficiency of wind turbined is limited by Betz's limit at around 60 %; the average efficiency of modern wind turbines is around 40 %.