I have a music blog that contains various embedded soundcloud and youtube players.
What I want to do is prevent any audio from playing simultaneously. In other words
it's possible. check widget api playground. you can watch all state events from soundcloud iframe widget. this can be done on flash embed too. https://w.soundcloud.com/player/api_playground.html
watch for SC.Widget.Events.PLAY {"loadedProgress":0,"currentPosition":0,"relativePosition":0} event on start playing