Media players should have a "playing" indicator that is separate from the play/pause control. Not just because of the ambiguity between state and action, but also because there is difference between the requested state and the actual state!

A media player can be in the "user wants to play" state and not be playing, because buffering is taking place. This is a very common state, yet all the media players I've seen have an ambiguous or confusing display during this state.