Looks like the FD is using water with a fome mixture to deplete the fire of oxagen which I can understand but I thought you were suppose to use dry chemicle on electrical fires.
Certain dry chems' can be corrosive to electrical equipment. A fog spray pattern is a good way to fight an electrical fire. Then when oil filled trannies are involved, use the foam!
I really like what these firefighters did, absolutely flood the entire area with foam. Here at Sequoyah, our procedure is the same.