I think the video said the system runs a cycle within a period of around 24 hours. What would it take to store energy in compressed air for ~6 months? This is what high-latitude dark-winter countries need: the ability to over-generate in the summer and draw down on stored energy in the winter.
Pumped hydroelectric storage is an obvious choice for the countries that have the geography, in effect meaning that most of the infrastructure for doing it is already in place. Hydroelectric reservoirs allow storing energy more or less indefinitely.
Of course, the capacity will rarely have been dimensioned for keeping 6 months of usage on hand, but combining pumped storage with over-provisioned wind energy would allow for living through months of unfavorable sun, rain or wind conditions.
