https://github.com/facebook/react-native/issues/41

"You can see this behavior in the UIExplorer app's <ScrollView> example. Fling to initiate a scroll in an inner ScrollView and fling again (before scrolling ends) to increase scroll momentum. Often times, this causes the scrolling to stop.

I haven't had gone through all of the ResponderEventPlugin code yet, but I'm seeing that when ResponderEventPlugin.extractEvents is called, the topLevelTargetID is sometimes incorrect.

The touches that unintentionally stop scrolling appear to be associated with the parent ScrollView instead of the inner ScrollView's content. I traced this down to RTCScrollView._shouldDisableScrollInteraction where [self isDescendantOfView:JSResponder] is sometimes YES. Forcing it to always return NO fixes the issue, but I'm pretty sure that's not the intention of this method :)"