Does it work just on chocolate?
It doesn't really "work" the way it sounds like.
It does not reduce the fat content!
If I understood correctly, chocolate needs to contain fat, so it stays "liquid" enough to go through pipes. Applying an electric field makes it "more liquid", so the fat content can be reduced -- but the electric field itself does not remove any fat.
The article was vague as it said scientists were able to reduce the fat content by 10%. What is not clear is if the baseline was 36% and then 10% below that. They also mentioned there was no commercial plans to develop.
Personally, I like my chocolate fat!