Ferocity Support Gem not working

Ferocity support seems bugged or I'm doing something wrong. I'm trying to experiment if I can speed up Warrior skills using ferocity support's +40% more skill speed; specifically Supercharged Slam after the changes.

I had success in generating frenzy charges for the skill to consume, but realized it didn't work on SCS even if frenzy charges are consumed.

I then proceeded to test with other skills, including the default mace strike. I generated 3 charges, and started swinging. No change in speed while consuming the 3 charges in 3 hits. After the charges were consumed, I kept swinging but noticed no change in the skill's speed either.

Does anyone know what I'm doing wrong or if ferocity support has been working for them?

If you want to see the test video, here's my reddit post:
https://www.reddit.com/r/pathofexile/comments/1hgui6p/ferocity_support_gem_not_working_or_just

Im not sure if im using it as intended, but ive been testing tempest flurry with ferocity, and im not seeing any buff or speed increase when i should be generating a charge