Let’s look at the spec of a turbine, e.g. Siemens SWT-6.0-154:
Nominal Power: 6 MW — This turbine produces 100 kWh every minute.
Rotor Diameter: 154m
Estimation of Size and Capacity
Based on the Video, there are four tubes, roughly the lenght of a propeller blade (≈70m), with a cross section of maybe 4 m². This results in a volume of ≈1000 m³.
The video also implies that there is one Ocean Grazer per turbine.
Fixed wind farms have a maximal depth of up to 50m, resulting in 5 bar of pressure. Note that this technology should be applicable to floating windfarms as well, at least in principle. Let’s work with 5 bar.
This results in:
Energy Storage: 100–150 kWh
This means that this facility could store all extra energy for at least one minute or produce full capacity energy for one minute if the turbine stops producing.
In practice, this would be a useful buffer that can level out fluctuations on the timescale of several minutes.
Ocean Grazer is more suited as a buffer (as capacitors are), rather than storage (as batteries are).