This unit looks great, but when I tried to implement it in game, the animations didn't work. If I tried to use the included animation (russiancossak.kfm), the unit didn't even show up in the pedia. When I used the regular cavalry or cossack animations, they didn't work -- the unit was stiff like a statue. I don't know what animation you were using in the screen shot, because it looks like the units are animated there, but it hasn't been working for me.
Anyone else having this problem? I'd really like to use this unit.