They key word being "felt"
I suspect kicks done may feel faster but won't necessarily BE faster.
It may be that the wearing of ankle weights simply tricks our body into thinking we're faster when we're not.
I'm not sure what the actual process is, but I figure it'd be something to do with feedback, proprioception. Similar to that heavy, "gravity suddenly got stronger" feeling one gets when jumping on the ground shortly after getting off a trampoline.
Then again, it might relate more closely to the "trick" whereby you try to lift something light which you expect to be much heavier (eg an empty tin you think is full) You then over-recruit motor units and lift it faster and/or higher than intended.
I guess the trampoline thing could be explained by an under-firing of motor units given the momentarily ingrained expectation of a much easier jump.
Either way, I feel these effects are merely short term tricks and wouldn't carry any long term benefit.