It now looks more like the firearms officer was in the middle of a vicious fight rather than just kicking the **** in the head for the fun of it.
I watched the leaked video,
Use of excessive force, including kicking in the head and seems reasonable to me, taking into account the context of what had just happened. (Police officers violently attacked, seconds before).
The guy sat on the bench, with his hands in the air - having only seconds beforehand, unloaded a flurry of punches onto an officer, use of excessive force there seems reasonable to me.
It seems ridiculous to me, they started a fight with armed police causing injuries and a violent scene, in return they got tasered, kicked in the head and beaten - then they all start playing the victim.
If that had been in the US, shots would have been fired.