In MVC definition it is said that the view can have full knowledge of Model. But the Model must not know directly the view. This said, Model can send update signals via an Observer pattern to any view listening for a specific update as it does not know its concrete classes.
In PureMVC for AS3 what you probably saw where view consuming VO coming from the model with an automatic update mechanism involved by the Flex Framework. This uses Observer pattern, the model doesn't know the view so it is always "pure MVC".