I think the theory is that if something is "still" moving after 10 seconds it's still the same "event" but just with a longer duration. So I think you won't get another alert. For a new alert, motion would have to stop first. Of course, all this being algorithm based, in reality, you may get something in between. If the motion dwindles enough it may see this as a period of no motion.
Perhaps someone from the MV team can confirm this. I haven't seen any documentation about this. @Saralyn, what do you say?