There is a large area of 5G at 3.5 Ghz around the town of Pamiers in the region of Cazaux in South West France. (The area identified in the Video posted above.)
5G at 3.5Ghz in France
Selecting the 5G button on the page will present both 700mhz (In Green) and 3.5gb (In Blue) just noting that it could be either that was used in the test.
Also the spectrogram display on the monitoring system in the helicopter was indicating 3.64 to 3.675 Ghz. I can only assume to be a range around 3.65 Ghz.
IG